I have manual windows, so I can't speak to the power window questions. But I did the window channel rubber on my driver door after rebuilding the vent window, and it wasn't a hassle at all. I just fished it past the glass. I seem to remember there being some clips on the back of the channel liner that pinned into receivers on the track, all I had to do was get the channel to the right spot and push and they popped into place. Overall I found replacing the window channel to be the easiest part of the process, getting the window glass in and out of the regulator was a pain, I scratched my door. And rebuilding the vent was also a bit of a tedious process.
I used PB's white spray lithium to grease the regulator rollers, hinge points and such, and PB's spray silicone to lube the inside of the window channel. Just poke the nozzle into the top of the channel, wrap a rag around the tube, and spray for a couple seconds, then run the window up and down.