From http://www.anandtech.com/show/9694/microsoft-reveals-the-surface-book (and some other websites) re: Surface Book
1) The tablet portion is 1.6 lbs (726 grams), so lighter than the surface pro, but still a bit heavier than he's looking for.
2) Screen size is good
3) I have a friend who said it's fanless who got to play with one, but I can't find documentation either way, and there do seem to be vents on the side of the tablet. It's possible it's just spitting in air from the base where there definately is a fan (for the GPU, if nothing else).
4) Yeah, no LTE that I can see.
5) No USB-C, unfortunately.
Edit:
I was curious, so talked to the microsoft store online chat people (take it with a grain of salt, this is the stuff I got from them though)-
3) the fan is powered down in tablet mode, and powers up when it's in laptop mode.