yes The big question is, will this skim coat adhere properly to the primer that is already on

There should be no adhesion issues.

BM Fresh Start is excellent. You can also use GARDZ, but it's clear. So if you're painting darker than white, use Fresh Start tinted close to finish color.

" Many of us were specialists in spraying primer and backrolling. We used 1 1/4" nap sleeves."

Holy Cow! Maybe that would be okay for section 8 housing with knockdown orange peel texture walls and popcorn ceilings. But not for the rest of civilization.

"1/2" would be more appropriate."

It would? That is still a lot of texture. Sounds like the OP want's smooth walls, and would be better off with a roller cover with no more than 3/16" or 1/4" nap.

" You should be able to find a painter that can paint."

I agree. But it takes a special kind of masochist to be a good house painter, and they charge accordingly.

You should expect a certain amount of roller stipple from a paintjob. If you want perfectly smooth walls, this is an abnormal request. As I said, the highly trained painter can get a wall to look just fine with any size nap. It's technique.

A roller cover isn't what makes smooth walls. It's the primer and the skill of the painter. I can use a 1/2" nap with SW Cashmere paint and it will dry level and very smooth. It's the technique. Roll it on, lay it off. etc.

If one is looking for Level 5 finish, get an estimate for Level 5 finish.

Well, painting is an odd career. There are some subjective aspects to it. It is possible to paint for your whole life and not be very good at certain aspects of the trade. Only about 10 percent of the customers seem to notice the stuff that I nitpick about.

Ever notice that customers very rarely look up at the ceilings? Countless times I have pointed out cracks, streaks, holidays, etc( let alone miles of cob webs) that they never noticed before.