Partitioning/Merging Questions

Hi everyone,

I'm a little confused with some things concerning Boot Camp and Windows XP. I have a retail version of XP Pro SP2, but I'm a little concerned with drive partitioning.

1) I only have a 120 GB drive and would like to keep as much space for OS X. Should I determine what I need for XP before or after partitioning?

2) Can partitions be deleted/modified after they're created? If so, what happens to the deleted space? Can I merge it with the OS X partition, if I decide to get rid of Windows?

3) Will Windows be able to see my Time Machine drive? If so, can I use that for extra storage or would that harm it?

Any pointers or other help would be greatly appreciated. If I have a misconception of something or am not really understanding how partitioning works, if you'd be willing to explain a bit so I understand better, that'd be great.

Thanks,
india349