Welcome to the forums
1. i haven't seen anything about that, but light leak generally means light can be seen where is shouldn't: either the screen does no go perfectly black when it should (it stays a little gray - usually called light bleed), or it "spews" through edges and parts of plastic that are not properly colored
2. dead pixels are pretty obvious, because they're either always dark or always lit up. Check your microphone, reception, see if the device reboots randomly, look around for more possible issues
3. you'll never get a correct answer for this type of questions; it's always your call
4. never tried, but there might be other problems beside speed, like your pc not having a public ip and therefore not being accessible from the larger internet. From my experience with vnc over ethernet (even that was slow), i don't think it would work to well
Have fun with your new toy!