Old one but a good one!
A few fundamentals to focus on when going overhead in the jerk:
1. Fast hands and fast feet
2. Barbell up during the dip
3. Hips back not chest forward
See more detail in the link here: Burgener – Dip
Stroke Rate and Split times for the rower are covered in the article link below. Ideal stroke rate for shorter rowing distances is around the 30 reps per minute range while staying within 5-10 seconds of max effort 500m row time. To read more click here.