Honest question for you: Is this trip about your girls or you/DH? It can be for both, but really just want to put it out there.
If seeing all of what HS has to offer, I'm guessing you'll need two days there so that you can do a combination of FPs and RD to get at least one chance on every headliner. I, personally, have not done Akershus and FEA, so I will defer to those that have firsthand experience. But, just in mid-January, my DD, mom, and I had breakfast at Garden Grill. A PPO ADR at 8:15. You can show up early (which I knew thanks to these boards!) - they will let you in whether you have a 8 am or 8:15 reservation. We were fortunate to be staying at Boardwalk, so we were at the International Gateway by 7:40 - they let us in shortly before 8 (maybe 7:50-7:55?). We were at GG by 8 am and got seated right away. Our server to us we could get down to Soarin' at 8:50 to be let in before the crowds coming in with the 9am regular open. It worked out perfectly.
Again, depending on what others say that have firsthand experience, I would suggest you get to the gate early, get your breakfast started as early as possible, and get right in line at FEA. You should have a slight lead over the regular open crowd. Then you'd have time to do FPs at HS. But, I think this only works if you can move your FPs around and try to get one of the headliners for that day that you hop over since you won't be able to get a BP for ROTR by the time you get over there. Just my two cents!