You can attatch more than one drive at once, but
it's better to use a cheapo 4 - way adapter (to
prevent possible damage to the "unbuffered" IDE
port).
As far as big drives, in my experience your best bet
is to use an alternate filesystem such as SFS or
PFS in conjunction with some "IDE - fix" software,
any 4 - way adapter you buy should come with it.
Configuring everything can be a pain but you'll
get it.