1. about the tremolos: what helped me (with this work, as well as with "con mortuis in lingua mortua" - which i actually found more challenging, tremolo-regarding) is constantly changing the active segment of the aparatus (work with the upper arm for 2 or 4 groups, then work the next 2 or 4 with the forearm, and so on) - this way, each segment gets time to relax while the other is working actively.
2. about splitting lh/rh the passage: i didn't, because it helped me relax my right arm (plus the fact that this is quite a relaxing passage, after the passage in broken octaves before...)
best luck