[G4] G4 Sawtooth AGP external hard drive request

[tommylaws1 at cox.net]

Newbie here:
I recently purchased a G4 AGP Sawtooth from a friend, then upgraded it to Tiger. However, it only has a 20 or 25gig harddrive and, I'd like to be able to have a firewire or comparable, BOOTABLE, external harddrive for it that I can copy my present, internal hard-drive, including the Mac Tiger OS to.
Several questions to all you more experienced and knowledgable folks out there, since I'm clueless.
1. Any recommendations as to a reasonably priced hard drive in the 250 gig range? (Smaller or larger OK too if you know of a great deal or other reason to go larger smaller). I'm not a techhie and am not doing a new version of StarWars on my computer.
2.Can my present drive be 'booted'/copied to the new drive without losing my present programs?  Is so, any help on how to do this would be appreciated.
3. Any idea on how to go wireless with this system?  I read a message on this forum several weeks ago about a Belkin USB wireless 'receiver' that some guy said worked for him. I purchased one but get no indication that it is recognized. No software came with it and, when I asked TigerDirect.com (where I bought the Belkin USB receiver) if I needed software to be compatible with my Linksys router, they said no. Range of the Linksys wireless router does not appear to be the issue, since my laptop works fine in the same room. Could it be a WEP issue, since I'm running WEP protection and the Belkin doesn't 'see' a WEP proteced system?
Anyway, any advice appreciated.
Tom