Don't be that lazy contractor. Of course you clean it.

Be careful with vacuuming it up! During our project, I unwisely used my regular household vacuum for sheetrock dust. Household vacs are not designed for that and mine seized up, dead as a doornail. Who knew?

Yes you clean it. You will miss some and subs will create some during trim out but make the effort

Yes, clean it.

Is this a reasonable expectation of our contractor? They’ve been very good about cleaning the dust accumulated on top of the floors, but not so much below the floors/between the joists.

I would request a good sweep through prior to insulation. Realistically the drywall people will create a ton of dust which will be immediately inaccessible inside the walls…

Expections should be in the contract. You may have hard felling when something you want is not provided. What is in your contract?

Nothing detailed in the contract about this.

If is not in the contracr, maybe you vacuum, i recommend A shop vac or similat.