I will address your questions to the best that I can.
1.) This depends on a lot of things. For one, from what I read DH likes to train in a more powerlifter oriented manner. So I would definitely put my bets on him saying 3x8 squats is bad. Infact, for strength or size doing 3x8 squats is not worth it when you can do 8x3 with a heavier weight. So if it comes to reps and stuff, I suggest you ask DH directly because he will be the best one to steer you in the right direction like he did with the exercise selection.
2.) There are many variations of Rows. So it depends on the variation that you are doing. I do not do barbell rows so I can't help you there. But with dumbbell rows and cable rows I see no need to deload. Yes, for Deadlifts deload. With SLDLs if you can, deload.
3.) You can just alternate. Week 1 with 3x8-12 and the Week 2 with 2x8-12. I hate arm work so I'm the wrong guy to answer this as this is something I would like to know too.
I hope DH comes on later and answers this for you
