Upgrading soon, 2 questions and my plan. Any recommended suggestions/changes

I managed to pick up a HR10-250 from a closing CompUSA the other day and have been more than happy with it since. However one of the biggest annoyances is that I don't have a phone line in my apartment so i haven't been able to get the unit to dial out and unlock the tivo subscription yet. I've tried using a sip box and serial connection without much luck so now I am moving to try and get the system network enabled via the linksys usb200m (v2.1) i just picked up.

I'm planning on upgrading the system to a 500gb primary hardrive (just trying to find a good priced one) and will be using the ptv network cd to add networking support. I will also be using the weakness boot cd to backup,transfer and save an image of my factory hardrive which will be put on the shelf after the new drive is prepared. I've done a lot of reading and there are only 2 questions left that I'm not 100% on and would appreciate any input.

If my subscription is not yet active ( I know I need one to utilize recording features) will I be able to activate it once i get my tivo networked via the linksys adapter, or do I need to find a friend with a real phone line to bring the unit over by them first so it can call out.

My second questions is hard drive limitations. I've read that my unit should have the updated kernel to support LBA48 for drives >137gb. Is there any top end limitation to the drive, i.e. will a 500gb or 750gb drive present issues trying to install.

I'm open to any other thoughts or suggestions about this plan.

HR10-250 Unit Specs:
Software Ver: 3.1.5-01-2-357