I also prefer the repeat.
Maybe you could practice relaxing starting from a very slow tempo with a metronome, and working it up in increments - like 8th note = 120 m, then 8th = 132, etc continued to your desired tempo (or even beyond). If you do this, do metric trills, so you are also trilling proportionately to the slow tempo and advancing with the same focus. The faster you go, the less movement is necessary - too much effort rotating could be locking your left hand (as could be holding it at a bad angle?). If I'm understand your third concern correctly, keeping your fingers fit in the chord could be contributing to the tension and fatigue blocking you from taking the repeat...here is where your arm should rotate moving your hand to the notes.
I would guess the general opinion in pedaling the last movement, would be as little as possible.
I'm working this out in my head...I hope some of it is helpful. I'd say practicing slow, metric trills as above will clean things up a bit.