If so how? I'm not very good with this root stuff, so I would need good instructions.
Sholes has everything BB has, BB has everything sholes has. they will all be equally updated. sholes makes it easier to update, stay with sm imo (if you have market sholes)
Not really. Pete has the new kernel in his that allows you to get CPU temps, and for me, while they have the same crap...BB has been much more bugless.
As for the answer of the original question...
Yes you can. Technically you can simply boot into recovery mode and install the update.zip from Pete's BB. However, I did a complete factory restore when I went from one to the other because I was having so many problems with Sholes and didn't want all that BS to transfer over to BB.
With my experience it was much worse with Sholes. When I went to BB 0.7.5 I also dropped 40ms in benchmark with MORE programs running than I had on Sholes.
Everyone has their own results, but something about the combination of apps that I have did not agree with Sholes and I have never had a single issue with BB. I had two battery pulls just installing Sholes (and that is common to get a battery pull or some FC while installing if you look around).
i would use petes instruction and do the nanodroid update including the wipe. that way no bugs that the sholes rom might have dont transfer over to the bb. not knocking any roms but ive read many times switching roms without wiping leads to more issues.