The only problem foreseeable problem is activating your phone again. When it comes down to rooting, it should NEVER conflict with you having a connection or not. The only problem you will have is once you update to 2.3. As you may or may not know, you will be unable to activate/reactivate your phone from a custom rom. However, you could get a jump start on using it anyway. Here's how I would do it.
1. Root your phone. Install Titanium backup and backup EVERYTHING. Keep the apk on your sd card.
2. Root your phone and install CWM.
4. Make a nandroid backup.
3. Flash your chosen rom.
4. Install titanium backup and restore all your apps.
5. When the time comes to reactivate your phone, Make a nandroid backup of your ROM build in cwm.
6. do a factory wipe and partion /data and /system
7. Restore your first backup of your STOCK.
8. Activate phone
9. Return to CWM. factory reset, wipe data and system.
10. Restore rom.
11. Enjoy your not-complete-shite phone.
If you need any help with CWM, flashing roms, which roms to choose, troubleshooting, or any of that, try the All things Root
hope this helps.