As for your healing question, I will answer that with a testimony. A few years ago I went on my husband's side of the bed to make it and his side is a huge mess. He had shoes and clothes on top of them and who knows what else but he gets upset if i clean it so I leave it. This one day, I went over there to make the bed, lost my balance and stepped on one of his piles and twisted my knee very badly. It instantly swelled. The next day, I was carrying a load of laundry downstairs and half way down the stairs I re-twisted that knee ever worse. The pain was so severe that it hurt to stand, sit, or lay down. I didnt have health insurace so I kept praying God would heal it. Almost a month later, I still had extreme pain and swelling. I was in bible school and we had chapel each morning before classes. This day, I was just tired of the pain so when the guest speakers had an alter call, I didn't go forward for prayer but I stood at the alter on the side and I prayed myself. I told God that I believe He is my healer and I wasn't going to leave the altar until I was healed because I couldnt take the pain any longer. A gentleman came and prayed for my knee and nothing happened. He left and I stayed there standing at the alter and talking to God. Later, he brought his wife and they prayed for me together and nothing happened but I believed so I stayed right there only I moved to the other side of the church so I could sit but was still up front. Then, that guy came back again with his wife and another woman from their church and they prayed for me again. I kept telling them that I wasn't leaving until I was healed and I didn't. I was determined to press and wait on God. This time, the pain instantly left my knee when they prayed for me but the swelling remained. I was able to sit, pain free, for the first time in weeks. I stayed at the alter again for a while praying but I did go to classes when they started. My final prayer to God was that I know He is a God that finishes the work He starts and I knew by faith that the swelling would go down. The swelling went up into my thigh so was quite bad. I went to bed with no pain but still swollen and I woke totally healed. So, when people ask me if I believe in healing, I have no doubt that God does heal. However, I don't think we have to have "great" faith. I kept reminding God that I have the faith of a mustard seed and that's all it takes. I don't know why God heals some and not others but I do believe that if we press in (even fast and pray if needed also), that we increase the chances of getting the answer we are seeking.
As for whether God knows everything alreaady, I hear that question a lot. I, for one, am still undecided but I feel that whether I have an answer to the question or not is not relevant in my life. I say this only because whether God knows what I will choose in advance or not, I'm just thankful that God still created me, knowing that I would make some bad choices. I'm also thankful that God does give me a choice and isn't dictating my life for me. That drives me even harder to try and seek God's ways and to try and make the right decisions the next time. I don't want to disobey God or make choices that do not please Him, but I know that God loves me unconditionally. If I mess up, Im still loved by the beloved. I feel that having this knowledge is enough for me.
Please know that I am not at all discrediting your question or how you feel about getting an answer to your question. I'm just sharing how I resolved that question for myself.