Most of my PBs I did HD upgrades too I put in an SSD or CF SSD. You should get 100GB or better for it. It is a PATA/EIDE connector and that ribbon cable is flimsy to take your time and do it slow when you do it.
10.4 or 10.5 would be great for it. My PBs G3/G4s have 10.4 with OS 9.22 on it. It can boot from the Firewire, USB and IDE Ports. In theory is should boot from the PCMCIA. I have not tried booting my 17in from the PCMCIA but I have booted from the 1400s, 5300s and 190s I have through the PCMCIA.
Carbon Clone Copier is one of the best cloning software for it.