Hi, Garry. Happy to see you asking questions. Looks like you're getting into it!
1. Around 65-66 average (big secret at WGT for obvious reasons.)
2. There are currently only 4 stroke play courses available. Kia, BPB SA and Oakmont. (Oakmont won't be available as a practice round until after the open.) You can access these courses under the Single Play tab in your game browser.
3. The percentage is the amount of the ball buried, 0% being fairway type lie. A good starting point for learning how much to adjust for these lies is 20-25%, add 1/2 club, 30-40%, add 1 club, 40-50% add 2 clubs.50-60% or worse means you're in trouble.Use a lofted club and get back in play. Shots out of roughs will run at the end so expect it.
Out of sand, pitching and flopping work well. Pitch if there's no bunker wall in the way. Flop over it if there is. Don't monkey with partial swings here until you're comfortable with what to use. Partial swings, for the most part, will keep you in the trap or just barely get you out.
Keep in mind, these are my general starting points-they worked for me until I learned my clubs. They should get you familiar enough with the lie affects to adjust to your style. GL