Just pick things you like and go to an artist that is capable of fitting the image to the available space. Some are extremely good at it and others are not.
Warriors and Gangs of New York are both iconic movies IMHO and I don't think you'd go wrong with either. Bill would probably be recognized by more people since it's a newer flick... if that kind of thing matters to you.
Holy Christ, that's nothing to mess with. Don't know where you're at, but that's the kind of thing that a local health department wants to know about. Whether you got it at the shop or had it before and took it to the shop they should know, have testing done and cleaned to hell and back.
Screw what people think about your tattoos. That's one of the biggest reasons that I started getting tattooed, I put up my entire life listening to people judge me and I decided that I was done with. Accept me tattoos and all or go F yourself.
It looks fine as is, don't worry about it. Every tattoo deforms as the skin moves, not much you can do about it. I think artists do what they can to compensate for it, but you can't make it perfect in every position.
Enjoy it and start planning your next one.
I understand what you're saying about being shy and starting here isn't a bad idea, but you're going to have to talk to artists (def. more than one). You'll have to pick someone with past experience and doesn't just sugar coat things to get the work. If you don't you'll just end up with an even bigger mess.
Probably 10 to 15 hours, but there's so many different things that can affect it. Best to find an artist who's work you like and has a good reputation, go for a consult and go with their estimate. Don't price shop. It's tacky and never results in the best quality tattoo.
My recommendation is to not start with a major piece. Pick out the artist you like and get a small/medium size piece. That way you learn the process and find out if the artist is all you wanted. Better to be disappointed with that than a huge one that you really want.