I suspect the OP is trolling, but I'll play along...
0) What should I do if my dad doesn’t come to a complete stop at a stop sign?
Be thankful that your dad is driving you around. Don't bother him.
0.5) I have trouble thinking before I act or speak; do you guys have any advice regarding this?
Think more. Talk less.
1) Is complaining in your thoughts a sin? (Lemme know if I should be more specific)
Probably not.
2) 1 Corinthians 13:11 says “When I was a child, I spoke like a child, I thought like a child, I reasoned like a child. When I became a man, I gave up childish ways (1 Corinthians 13:11 ESV).
So, I’m a teen, and in the past, at least once, I’ve wielded an inanimate object such as an iPad, and while I don’t believe I was consciously pretending and imagining it was a gun per say, I made a recoil motion and probably subconsciously imagined something firing out the end. Basically I used it as a pretend gun, I suppose.
My question is, would this be a sin or is it alright?
Not a sin.
3) Is being what today’s society would consider “nerdy,” “dorky,” or a “geek” a sin?
Not a sin.
4) Is saying something like “my parents would kill me if I did that” a sin? (Because you’re using the word kill in that way)
Not a sin.
5) Is taking a long, hot shower a sin?
Potentially. Especially if you're doing other "activities" in there.
6) what’s the difference between changing your mind about something and being hypocritical about something?
Hypocrisy is saying something is wrong for other people to do, but when you do the same thing it's suddenly okay.
7) I understand that language barriers exist and that trying to use the phonetic system of a different language can be difficult, but is it a sin to find an accent funny?
Not a sin.
8) I feel like this is one is a sin, but confirmation would probably solidify it: is is being mean to yourself a sin?
Need more info.
9) What should I do if a stranger on the Internet might have been neutral or even trying to have been nice, but since text lacks tone, they came off in a way that kinda hurt me
Toughen up. Stop being a sissy.
10) Is feeling (and accepting it) anxious for a second or two a sin?
Probably not.
11) I’m <18 and a lot of stuff I’ve accepted, signed up for, downloaded, etc., I’ve accepted their Terms and Conditions (or some equivalent or variant) without reading or skimming through. I doubt I should go back and check everything, but, what should I do?
No one reads that stuff. They're going to track you, sell your information, and scam you regardless of whatever it says.
12) Is being what today’s society would consider “weird” a sin? (I’m sure you’d need specific if you were to try to answer)
Potentially. "weird" is probably going to wind up being in rebellion to God in some way.
13) Is sitting alone at school lunch a sin? (It might help for me to provide more context and information regarding this)
No. but it's not good.
14) Is not being in a state where you typically have fellowship a sin?
??
15a) I have a teacher who likes to funnily mess with his students. If he tries making someone flinch by making a sudden loud motion and noise, and I laugh, is that a sin?
Not a sin.
15b) Would it be a sin to find it funny but not laugh?
hmmm... I doubt it.
16) If you’re in prayer, and you feel intrusive thoughts coming in interrupting your prayer, is it a sin to say “shush you” or “shhh” (basically, not talking to God, but I suppose you’re talking to your thoughts, while you’re in prayer)
Not a sin. I suspect God has a pretty good idea what you're saying and and who you're talking to.
17) If I’m watching videos that I perceive to be monotonous and I’m almost done with them and I have a thought such as “thank the good Lord himself,” and assuming I wasn’t trying to take His name in vain, is that a sin?
Not a sin, but I think I'd be a little mindful.
18) (If I may preface this, I’m not trying to necessarily find an excuse to not comb my hair, I just want confirmation haha) Is coming to school with messy hair a sin?
Not a sin.
19) Is using the word “gay” as a substitute for “uncool,” “cringey,” or “weird” a sin?
Not a sin.
20) Is using the phrase “I swear” in a jestful manner (see Ephesians 5:4) a sin? Hypothetically, let’s say I say to someone who I’m good friends with in a playful manner and joking tone, “Bro, I swear, you poke me one more time, and I’m finna smack those shins, boy” (not that I’m trying to condone serious violence).
I would advise against this.
21) I think I read somewhere about speaking up against injustice (I believe this was regarding maybe police brutality and BLM or something) and it was talking about posting stuff for like awareness and calling out injustice or something on like social media. But I think they called not speaking up for others (regarding that kind of stuff) a sin of omission. I’m >18, I live in the US, and I doubt my parents would want me to get involved in that kind of stuff. Is it a sin of omission in my case?
Stay out of politics. People will try to recruit you to their cause. They're trying to exploit you.
22) Is transferring drinking water to another container in a manner that causes a good bit of it to be spilled into the sink a sin?
If this is a sin, then a long hot shower is a super sin.
23) Is it a sin to find a heated debate interesting?
Not a sin.
24) If you’re about to look at some racist, back in the day, political cartoons (that give the vibe of, “that’d be very controversial today,” is it a sin to have a thought like “I can’t wait to look at these!” and look forward to it?
Not a sin.
25) I feel like this one is a sin, but you can take God’s name in vain in your thoughts right? As in it doesn’t have to be verbal.
Your thoughts can be sinful also.
26a) Is it a sin to sing along in your head to lyrics that say “I swear to God” but also not be consciously aware that you might be taking God’s name in vain?
Probably a sin. But you should understand that taking God's name in vain encompasses a lot more than “I swear to God”
27) If someone’s online personality and voice comes off as “gay,” (not like, just homosexual, but rather, I’m not sure if I’m gonna phrase this right, but, in the vernacular) is it a sin to think “he’s so gay! I love it”
If you like the gay because it's gay, then it's sin. A big, big sin. Sodomites are in open rebellion to God. If you love that, then you love rebellion to God. Stop worrying about all the other stuff and take care of this issue. Seriously.
28) Is it okay to talk about *ahem,* sexual topics on this forum?
I don't make the rules.
29) Let’s say typing is an important part of your work and/or school life and requires a lot of your time. Let’s say you’re inefficient at typing and could be better; assuming you have the time, is it sin to not set aside time to become more efficient at typing, which would give you more time to do other things? (see Eph 5:16)
Stop worrying so much about stupid stuff. Deal with question 27. Focus on knowing your God a bit more.
30) Is having thoughts like “I went through heck” or “I went through hell” a sin?
Not a sin. But you're probably exaggerating whatever it was that you went through. That would be a sin.
31) If you have a thought you don’t like come in, is telling yourself to “shhh” during prayer a sin? (rather than talking to your thoughts, this is I suppose, talking to yourself)
Didn't you already ask this? Deal with #27.
32) Is someone’s name (or username or nickname) necessary for intercession?
No. Prayer is not like Death Note. You don't need a face or a name.
33) If I did a bad job with apologetics years ago to people on the Internet (let my emotions get in my way, and maybe said some stuff that, looking back, ain’t true about stuff like God maybe, the Bible, Jesus maybe) who I used to be somewhat of an acquaintance with but haven’t talked in a while, what should I do?
Understand that you get better at stuff as you get more experience.
34) I’ve been really neglecting praying for distant family to get saved, is this a sin?
I don't know. Instead of worrying about whether or not it's a sin, why not just pray for them?