I am not sure to what exercises this volume refers, but it seems a bit too much to me. Perhaps a 3 x 10, 4 x 8, 5 x 5 would work well towards maximum strength in your case, keeping the volume relatively the same. As for your last question, I think it's better to wait and see the response to these exercises first and the improvement you'll have in the rest of the exercises and then decide. But if you want to improve something, starting with it usually works well and this is the time/phase to do it, since the rest are still in the development stage. I hope this helps.