1. Yes.
2. Excellent.
3. Comparable. Didn't really see a difference.
4. Not at all. People root it for extra audio options that are either unnecessary or available via other (cheap) options. But, IMO, it's not needed at all.
5. Yes. I think Max is 2TB?
Agreed.
It seems people are only rooting their phones because they're bored, are running poorly matched headphones or don't understand how the LG's headphone output actually works.