Here’s the funny thing, he actually says for PL you don’t necessarily need to add sets each week since the overall goal is to get stronger and pushing volume too high will compromise that. They way he wrote the recommendations in “Scientific Principles” is kind of vague, but what it says is to add weight and/or sets each week, more sets is not necessarily required. He discussed this in his presentation in that “Online PL Summit” or whatever they call that thing that Koevoets guy runs. You can start each hypertrophy/volume block with a lower volume week if you tend to get real sore the first week after a deload but basically you want to maintain a sustainable volume that will allow you to get 4-6 weeks of hard training before you deload again.
As far as total number of sets for MRV and whatever else, that is going to depend on you as an individual as well as what sort of training block you are in and how you set up your training. Mike likes the idea of strength/intensity blocks being all heavy lifts in the 3-6 rep range and no isolation work or high rep assistance stuff, that is one way of doing things but it isn’t absolutely necessary either. I find that if I do that I start to lose a bit of muscle after a month or so, if you take PEDs then you won’t have to worry about that so much but at the same time Chad Wesley Smith doesn’t program the same way as Israetel. Programming is more of an art than a science.
Yes and no. If you don’t care about strength then you can bulk hard and gain a bit of fat then do a cut and lose the extra fat and repeat, that’s what Israetel has been doing since he weighed like 220 or so. For PL it’s not really a good idea because you will get weaker when you cut, it’s better to avoid cutting unless you are just too fat. So what you do is hypertrophy phase for 3 months in a caloric surplus - but aim to gain maybe 2lbs/month so that you don’t add much fat, then intensity block for 1-3 months and calories at maintenance. Just keep repeating and you will get bigger and stronger.
Also, if you end up getting a little fatter than you like after a couple months of low volume training then a recomp can work well - keep calories at maintenance (you might even have to increase them) and increase training volume, you can lose fat and gain muscle at the same time if your body is in a state where it’s extra responsive to training volume. I asked Israetel about this on facebook a couple years ago because he was saying that losing fat while gaining muscle only works if you either haven’t been training or just started taking PEDs, neither of those were my case and I made it work. What he said is that essentially there was a detraining effect as a result of low volume training and peaking for a meet (I also took a week off training after the meet) so I was more or less in the same situation as someone who had taken a long break from training.