No. You have to live with numbers in your name forever.

I seriously doubt it because people keep using inappropriate names which means Bungie has to waste time resetting those names and sometimes banning the player. If people didn't use -blam!- references and other inappropriate content in their online names we wouldn't be restricted to one name change. Blame the community for the one name change, not Bungie. To be honest, one name change is more than enough. Nobody needs to constantly update their username. It's just a name, pick a name and stick with it.

Yes

No.

No, you messed up, there is no fixing it, your name was a one time change...

Probably not since they're obviously winding D2 down, and will likely make another forum overhaul, granting people the option to change their names to something else they end up hating that too.