1 - Depends. I've read and liked both. Some of my favorite novels have multiple characters that weave in and out of a greater tapestry. At the same time, some of my favorite novels also follow once character from beginning to end. I will say, however, that the former takes more skill and dedication from the author.
2 - Third person, I think, is superior for telling complex stories.
3 - Either is fine, though I find that novels with nebulous characters have the potential to be more intriguing. Especially in fantasy, formulaic good guys/bad guys plots can get a bit tiresome.
4 - Inconsequential details don't really appeal to me. I don't care to know about brand names unless there is a point. In Donaldson's Gap Cycle, there are company names used but it's really an indirect way of reinforcing the idea that there are a few mega-corporations that run things.
5 - Technology branding depends on the story and what it's trying to say.
6 - Humans vs. Aliens is mostly played out, unless it's orchestrated in a new and unique way. Human vs. Human is almost always more compelling. It's even better when layered, though. Again using the Gap Cycle as an example, the author uses the greater alien threat as a backdrop to a story that is 90% humans trying to kill or use one another.
7 - I usually prefer more realistic science fiction, though it completely depends. The skill and talent of the author is more important.
8 - Song of Ice and Fire. I've only read a little of the Wheel of Time stuff but it felt too fluffy.
