Hi @Carlos D,
Question 1:
Yes. It's better. You can also add another node if your situation allows it. The ideal environment is to have a primary replica on one node and only secondary replicas on the last node.
Node1: primary replica secondary replica
Node2: secondary replica primary replica
Node3: secondary replica secondary replica
Question 2:
Yes. Trace Flag 3459 disables parallel redo without a SQL restart. Please refer to this blog: IRL #6: Availability Group Performance
Best regards,
Seeya
If the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".