iOS update/sync to new computer

Hello everyone, and sorry if this has been answered before but I felt that my situation was so embarrassingly ridiculous, I did not think this was possible.

I have a MacBook that I bought in 2007 that I love dearly. I also have an iPhone 3GS synced to my MacBook. The problem is, my hard-drive crashed awhile back and I am running Tiger as well as the "newest" iTunes that Tiger can run. I cannot update my iOS past 3 using Tiger. I also have all my music on this MacBook.

I recently bought a cheap PC laptop that can support iTunes to update my iOS on my phone to 5.01. I have both my MacBook and PC authorized for my account on iTunes but I'm just not sure if I'll lose everything if I update iOS on my PC.

I have two "big" questions:
1) If I update my iOS on my PC, will I lose the apps I have purchased from the app store?

2) If I update my iOS on my PC, can I "resync" to my MacBook to transfer my music back from this computer and keep the iOS 5.01 on my iPhone?

Any input would be very helpful. I have searched things like "how to sync my iPhone to 2 computers" but I feel that my endless loop of outdated-ness may be my downfall here.

Thanks again; I always look here for Mac help if I have issues, but am a first time poster (multi-time lurker).

1. No, provided you sign in to the same iTunes account on the PC that you used on your Mac.

2. No. You'll want to transfer your music (et al) to iTunes on the PC and let that be the new "sync point" for your iPhone. It can only be tied to one device, and cannot sync to more than one device.

Thank you very much---I had a feeling it would end up this way but I thought I'd get a second opinion