Thank you for joining! I am the person who advertised at SMWCentral, and I'm entirely grateful you joined! Addressing your questions:
At the current moment we are only hosting "official" mario games. If you look in the top left of the site window, there are video game characters showing off all the subsites. Click the "sonic" icon and you will be able to notice how well developed and populated that site is. It took years for that site, at its development level, to begin to entertain the thought of running "unofficial" sonic games (read:hacks). Eventually the idea was used and the "tails" icon is the result (if you click around you can get back to this forum by pressing mario >_>). The site has shown very little in ways of development, even starting with a huge sonic fanbase already alive. It will be a long time before we entertain the thought of mario hacks on the site.
As to your second part... what do you mean, hack the game to be small mario? It is easy to start levels as small mario. you -are- allowed to get powerups midlevel, you just can't start with them. The main reason for this is we don't want all the times to be runs where someone just flew over the top of the level with a cape. All you need to do is start as small mario, which is fairly easy to do.We would appreciate it if you used the official game for the runs, even considering laziness.
Hope that helps; Welcome to TMC and hope to see you on the charts!