I'm glad the site has been so helpful to you...it's been a lifesaver for me too!
He can go to 3 meals whenever you're ready. I think we had Tyler on 3 meals about 2 mo after we'd started solids, but some babies move faster than that. It's really up to you and your DS. I know that's not a very good answer, but there's really no guidelines that I know of for when he should be on 3 meals a day. Someone correct me if I'm wrong!
It's hard to know when he's ready to try finger foods. He'll most certainly let you know when he prefers them, but that comes later. If he's doing well with more textured food, you can give it a try. We started with cheerios...your best bet is to start with somethat that will dissolve easily in his mouth. The first few times, I soaked the cheerio in water or milk first to soften it up and gave it to him from my fingers. As he got used to it, I gradually soaked it less and less until he was eating the real thing. Then we let him try self feeding and we moved on to other finger foods, like soft fruits chunks. HTH!