While I can't speak on aaditya's behalf perfectly, I will try my best. If I miss something, please correct me.
It wouldnt cost anything to be hosted, even with a domain name, with either one of us.
Yes, both of those forum packages allow for that to be accomplished.
If you mean which forum software is better, I believe personally that Invision Board is the better of the two [even though its an older version, due to licensing changes], but then again phpBB continues to push forward. It really comes down to personal preference.
If you happen to mean which hosting service would be better, that is completely up to you. I don't believe in "stealing" users from other hosting services, I just want everybody that deserves hosting to find whatever they need, whether that be with me or someone else's service. It appears that they offer 1gb of transfer, I can't seem to find out how much space due to a mySQL issue with their forums. I set up all of my accounts different everytime, so everybody gets what they really need. I am sure either way you go, you'd be pleased.
