When you are in the installer press alt+f2 (or what key on the mac) to go to another terminal. log in as root (if you are not already locked in, canīt remember how it works in the install) Then start cfdisk . Itīs the partiniotating tool that debian install uses. Itīs pretty easy too use, so go on from there.
About the amount off swapdisk, i have 128 MB of real ram, and a swap partition on 256 MB, and never had any problems with it. For instance right now, my load looks like this, with kde3, evolution & galeon running:
total used free
Mem: 123 117 5
Swap: 243 84 158
And KDE is REAL heavy, when it comes too ram, when i used fluxbox, i rarely used the swap.
Docs: look at the debian website http://www.debian.org/doc/