Will you only be visiting for one day or will you have more than one day? Will you have MP? How many in your group and what ages? Is everyone tall enough to ride MFSR and all the other fast rides? (When you say "the new Galaxy's Edge Ride," do you mean MFSR? ROTR won't open at DL until January 17, 2020.) Will you have park hoppers or only be visiting DL? Will you be at the parks for RD and stay until closing? The answers to these questions will help us give better answers to your questions.
For example, if you will have a 3+ day ticket with a MM, you can use that to take care of SM and Matterhorn, then go right to BTMRR after the park opens. MP can help you take care of Splash, as well as any other thrill rides like IJA, GOTG, IC, RSR, etc. (assuming you will have MP and park hoppers). The app can help you time your ride on MFSR -- just keep watching for whenever the ride has a wait time of less than 40 minutes or so, then jump in line. And don't forget to use the SR lines -- if everyone in your group is 7 or over, you can take advantage of SR for repeat rides.