You have made some great discoveries! Prep is indeed half the shave, and without good prep the shave just isn't satisfactory.
Before I got a large scuttle a couple of weeks ago, I used a large cappuccino cup with a handle, and kept it in my bathroom sink filled up half way with hot tap water. This worked well enough to keep the bowl warm.
XTG passes are also tricky on my neck. i have the best luck shaving in from the ear side of my neck to the center. I can only get a small portion of the area with a stroke, although it is getting easier with time.
I get 7 shaves per blade. This is very prep dependent to me. I used to get 3 shaves per Feather. Replace your blade when it tugs, skips, or feels rough on your face.
Have fun shaving!
i'd rather learn from one bird how to sing than to teach ten thousand stars how not to dance. e. e. cummings