Awesome, welcome to the linux community
I can't answer most of your questions with much confidence, because i'm still rather new to linux myself -- well, i've been at it a while, but don't have time to really dedicate
to learning it as much as i'd like to -- but i can try to answer about the Windows partition..
Do you want to to keep it, or are you planning on erasing windows all together? If you want to keep it, you'll have to tweak the partitions (unless you have a blank partition already), and i believe that can be done with linux, but i'm not sure exactly how. But i do know you can use a program like Partition Magic in Windows that will allow you to change partition sizes.
If, on the other hand, you simply want to get rid of windows all together, the installer will make that a very simple choice, something like "use entire FJTS120G drive" or whatever.. and that will wipe it all.
Also, you asked if its pretty straightforward. Well, that really depends on how much computer knowledge you have. If your idea of a fun weekend is doing computer forensics on your friends crashed PC, well, this will be a piece of cake. But, if you don't even have a clue what "defragmenting" a drive is, it could be a challenge -- and those are some very
broad generalizations. It also varies from one distro to another; I just installed Mandriva 2007 yesterday, and it was by a good margin, the easiest distro i've ever installed. But, on the other hand, i installed Slackware a while ago, and chose some option i shouldn't have, and had to reinstall it almost directly after because of my idiotic mistake, lol.
Hope that helps, and i hope that your installation and experience at large goes well!