I try to rotate my forearm and practice with a metronome now.
1) Forearm rotation is OK to practise, but its function is to move the finger to the right place/position on the next key (with a little lateral movement of the upper arm if necessary). It should never replace finger(tip) activity. Forearm rotation without alert fingers may lead to trouble and pain in the wrist area.
2) Do not use raw physical strength to bring the key down. You need just a tiny movement with your fingertip to sound a note, not brute force.
3) While organizing/planning your actions, "lead" the broken octaves with your thumb. Practise the passage with thumb alone first until you are comfortable and then add the pinky. The pinky note is merely an "echo" of the thumb note and should take care of itself. Also avoid excessive stretching and bracing with the fingers. Just open your hand slightly to play that next note for only as long as necessary.
4) Dynamics: For the time being, work in the mf zone. The fortes will be no problem as soon as you are really at ease with the material.
5) Practising with a metronome while you are still unsure of how to play the notes comfortably is harmful. Do yourself a favor and stop doing that.