I plan to have our (45-year old) in-suit Master & Shared Bath Rooms gutted & redone early next spring, and wonder what specifications should I require. My personal peeves are:

(1) I want threaded plumbing bibs where applicable because the existing compression fittings (wherever I lived) leave no pipe length for replacement.
(2) What should I specify to have a firm subfloor to avoid tile cracking.
The master is on the 1st floor which is on a "thin" concrete floor (over a walkout basement & side loading below grade garage). I have a few hairline tile cracks which I assume is normal for 45 years, even on a concrete base.
Anything to require, to avoid tile floor cracks or pressure on grout ?

The shared bath is on the 2nd floor, and also have some hairline tile cracks. Is it typical to replace the wood subfloor .. . should I specify that the subfloor be screwed in to joists. Even with "good contractors", leaving it to their professional standards can result in a wide range of results.

(3) The house has distinct trim & casing -- in other repairs & renovations, contractors got what Home Despot had which didn't match. A ACE store w/ wood milling said they can custom make most/any trim if we provide a sample (to set up a cutting bit).
I suppose I'll specific the use of the trim pieces.

(4) The previous owner put lipstick on a pig by using latex paint over oil on the master door (nice original solid core door) and other places -- feakin' redneck. Can I salvage the door ?

(5) The rest of my 2nd floor (original 1965 hardwood) has become very squeaky. There's some deflection in spots (I feel them rather than see the ponding), and I can feel the floor planks having some space between them (presumably due to wood shrinkage). Assuming no structual issue, I think the standard way to stop the squeaks is to screw the planks to joists, and putty over the screw heads.

I don't expect the Bath contractor to deal with this, but post in case someone can inform.

(6) In general, what "technical requirements" should I ask for in the Scope of Work ?