Lol happens a lot! I used to just bring a bed in my bag, so in case I get lost, I can just sleep anywhere lol. It's just a block on the floor where the mobs come out, I haven't noticed if there were indicators, but they won't be hidden, at least they shouldn't be. You can even build a cage (I don't know how though) on the mob spawn point so when they come out, you can easily kill them for xp! Well the map, you'll need empty papers (from sugar cane) and a compass. Compass requires red stone :/ and iron. But you can find them in chests too, or buy them from the villagers in exchange for emerald.