Battery life depends on what your are doing. Games with graphics eat it up fast - about 4 hours max (world of warships is a good example). Video playback is better at 6+ hours depending on volume and screen brightness. General office use (email, word, etc.) and web browsing probably 10+ hours in real world use. Standby is great even with cellular. I’ve gone a couple days using it as I travel on the road without needing to charge it while just checking emails periodically and using work websites in between client visits.
Is it less that I’d like - yes. It’s a big screen with a fast processor in a light package so how much battery can really be crammed into it? Ultimately it’s so easy to charge anywhere a usb connection is available (airports, airplanes, cars, meeting rooms) that it doesn’t effect my workflow.

No, it's not. It's easy to clean though.

No, Windows Home - you can always upgrade it.

It's Overkill.
Any dual core Core series (I3, I5, I7) mobile chip (u series) with integrated graphic would process any video stream just fine. The internet connection at your home/office and the WiFi antennae on the laptop are more important. This is a mid level game machine or a good portable video editing machine. You'd also probably get let down by the battery life since there's a lot of horsepower and a really big screen to use up the small battery quite fast.