Question 1. Back
Placing Jh in the back row gives you advantage over Villain in all three rows. In addition, Villain is carrying two spades in his hand, which depletes your chance of catching your back row flush.
Question 2. Middle
Placing Jh in the back row is not enough to beat villain's back row trips. Furthermore, Villain is not carrying any spades so you still have 10 spades in the deck to hit your back row flush.
Your front row is currently ahead of Villain's front row, so conceding the row with no significant improvement is not ideal. You should be looking to catch a pair up front.