new men's player, need help with rules

[donm5]

Sorry for boring with this basic rule quetion...
I'm a brand new player to a Men's 12" slowpitch league, played with ASA rules...

Does anyone feel like explaining the ASA substitution rules?
Also, does every position player need to bat (DH for a pitcher allowed)?

I wouldn't have to bother with these questions if the ASA Rulebook was available to meer peasants of the game like myself! Thanks!