lam prep question
I'm surprised at the advice you got from a flooring stoor.
First of all, your 3/4" T & G is adequate. Just make sure that there are no nails popping and secure it to the joists with extra screws. You dont want squeaks, especially after you lay the laminate. All that is required on top of the subfloor is a thin foam that comes in rolls and this deadens the sound that you would normally get from a wood floor. Dont fix the laminate, let it float and leave a 3/8" gap between the laminate and the walls for expansion or you could get buckling. Your trim or quarter round will cover this.