1. Possibly. Laptops are far more likely to thermal throttle though. Also the CPU is weaker than the desktop counterpart, so YMMV.
2. 10 on 1920x1080. I wouldn't be keen myself. You can always try it on a desktop first. things to remember is that a 17" screen is small these days, and boxing tends to require pixels and realestate (or you just need to really squint). I find 5 or 6 on a Full HD hard.
3. No. Maybe. Depends on whether you really want no interruption. You could end up waiting for the next GFX after that, and then the next CPU, and then the next GPU, and then the next SDD, and then the next memory gen.
4. I've ended up with multiple laptops. If your role supplying the Surface Book limits you so you can't use that during a meeting (presumably for notes or a demo/powerpoint), then I'd be inclined to go work laptop and separate play laptop. I have a reasonable, but not over the top Dell for work (actually using it now too. Actually I have two of them for work, one is the portable one and the other is my work desktop replacement. Then there is the gaming machine. Going through airports is not fun, but other than that it works out. The most annoying thing is keeping a few things in sync that I want to be.