teach me about partitioning please

[00se7en]

so i know a little bit about partitioning--enough to get multiple os's installed without destroying them, but i have some questions.

 

what is the difference between an extended and a primary partition?

do all os's have to be on primary partitions?

is there a limit to only 4 partitions on a disk? (ubuntu told me this)

 

if i have a 120 gb hard disk and i want the following os's on it, what is the best way to partition?

osx

suse

ubuntu

 

can i do something like this?

osx

/ (suse)

/ (ubuntu)

/swap (for both suse and ubuntu)

/home (can i share a home partition between both suse and ubuntu or is this bad?)

fat32 (like a scratch drive where i could put stuff to get at it from windows which is installed on a whole other hard disk

 

this is 6 partitions though, so is that possible? maybe if i understood extended partitions?

 

thanks to anyone who can help.