Without knowing where you are located, it is hard to make a recommendation as to what program you should try for miles. Also, you didn't mention spending habits on credit cards.

Technically, it is possible. But it would be very hard to get 8 seats on the same award flight unless you did the anytime or double miles awards. In that case, it really would take a lot of miles.

Considering where you want to fly out of, pick a frequent flyer program with a hub in your area. Since you have Ultimate Rewards points, United could be an option. American is an unknown right now because of the merger.

When do you want to make the trip?