There are a lot of threads in the Practical Travel Safety Issues forum covering pre-check and how to get it. Do a search and you'll find many. Basically, it's easier screening through TSA checkpoints (no shoe or laptop removal). There are a number of ways to get it, but becoming GE is one of the easiest.

GE is very worth it, even if you only travel abroad 2 - 4 times a year. From the aircraft door to the exit doors of the customs area is typically about 7 minutes for me (with carryons). If time is your most precious commodity, it's well worth the $100.

You can schedule the interview pretty much around your own schedule and at any GE facility, which means any time you're flying to another airport with GE, you can interview there.

(This is a practical question covering practical topics... should be in the practical issues forum.)