emusonacid! legacy

hi,

my macbook pro was recently stolen so i'm back to the emu (e6400 ultra with rfx card) and my trusty atari st (i hope it still works)!

as i'm gonna be using the emu live (instead of logic / mainstage) i need some onboard storage - i used to just use zip disks in the studio - but i don't want to rely on a hard drive for live use.

the questions i have are these:

where do i get the simms from?
what kind do i need (the whole ram / rom / flash thing is confusing me)?
how big can they be and how many can i install at once?
will this affect the amount of ram i'm using (from memory - sorry for the pun - i think i've got 72mb - not rigged it back up yet)?

thanks in advance. :-)