It doesn't matter whose mileage account holds or tickets the flights, if the flyer has no status-no E+. If you are flying on the same flights in coach you can absolutly take you and 1 companion into E+, it doesn't matter if the miles come from yours or their account. If you are flying with more then 1 companion, again it doesn't matter whose account holds the tickets, you most likely will not be able to get everyone pre-assigned E+ seats, just you and one other. The exception is if you get a nice agent over the phone to make an exception.

As for question 2, the same would rules would apply, although I have never done this I can't imagine it being different.