1. Yes.
2. Yes.
3. I do not know terribly much about the topic, though I do believe it is a sin. I cannot back it up well though. It's my opinion.
4. I believe we are all born sinners. I am more susceptible to falling into certain sins than maybe you are, and you are more susceptible to falling into others. I think homosexuality is no different. It's also no worse than any of the other sins. "Bad and worse" sins, a rating system if you will, is a HUMAN construct, COMPLETELY. It's all sin in God's eyes. I think we choose to sin and choose to be separate or we choose to come to know God and God gives us the way, through His Son, a way to be purified. I don't think simply being attracted to the same sex though is a sin. I am attracted to men (I am female). That's not sinful. Maybe Joe is attracted to men too. That inherently is not sinful. What is sinful, however, is lustful thoughts because of that attraction or further, lustful actions. I think both can be helped. You can train your mind to stray away from those thoughts and turn them off if they start to happen. Actions you have the power to say "No" to. So, in short, yes, we are all sinful people, but God gave us a way out, through His Son. GRACE. Forgiveness. Mercy.