Couple of ideas for you:
- you're getting the communication error... are you using pc or mac? I tried using windows through parallels on a mac, and had a heck of a time, so I always only use a pc now. Also, I've heard vista has issues (beyond my scope).
- If it won't even start ruu, maybe you have a corrupt file. Try downloading the rom again. You are trying the official sprint rom, right? That way you get the new radio, etc. That is the correct first step. I think that's what you said you are doing, but just want to make sure.
- about the 11% thing. How long did you let it run? I've upgraded 2 phones now, and both of them hung at 11% for a while, but eventually picked up again. Just let it sit for a while and see what happens.
- Are you unlocked??? I guess that should have been my first question. If you are not unlocked, you will get nowhere. That is step #1. Here is the thread for the unlocker:
http://forum.ppcgeeks.com/showthread.php?t=9093 Unlocking will not change your rom, it just allows you to put other roms on. It works through ruu, but in the end your phone will boot back into the old rom, as if nothing changed. Then, once you are fully unlocked, you run the sprint upgrade, then you run a custom rom (such as no2chem, like you said).
If nothing here helps, give us some more details, and tell us how these recommendations failed.