To create a channel, type /join #<channelname>, which is whatever you want it to be called, and if it doesn't have ChanServ, then it's not registered. Type /cs REGISTER #<channelname> to register the channel and have ChanServ come over and join it. However, that's all I know about channels and bots, because it gets more complicated after that, If you want to use other bots like Axiom did with Luigibot, it will require a lot of coding.
As for software to make graphics, Paint.NET is heavily recommended.
Download it here.
To replace the standard SMBX sound effects, first back up your sound folder (in case you want the original ones back), find your sound effects, and replace them with the appropriate ones in the sound folder (not the backed-up one). For example, if I want to use the heart sound effect from OoT, I would name it "zelda-heart" and replace it with the zelda-heart that is in the sound folder.