welcome
as for programs: You will need some way to upload you files (either directly or via ftp) and some sort of text-edit program. I guess everything is fine. Even notepad. I can't really give you any advice on what program to use. I simply use BBEdit, since it's the only coding-app I know for mac.
I guess all bbg-devs use different programs. As I said. Use what you are most comfortable with.
If you mean programs as libraries or classes that all game makers use, you might want to check out adodb. I guess this is pretty popular, or at least almos all recommend using it.
As for the legal aspect: You need to pass the bbg-dev test at
http://www.AmIDevOrNot.com . Naj, just kidding. As far as I know you are free to create your own bbg. As long as you inform your user at what kind of terms you offer your game, there should be no problem. If there were any legal aspects, I'd be in much troube
