Latitude 5540 m.2 and options

I have the opportunity to get a latitude 5540, but I have two questions for which I can't find answers by search. Maybe someone here can give me the information I need.

There are a bunch of different versions of this unit, each one having different features. Particular features, like the CPU and video, cannot be changed. What you have is what you're stuck with.

I wanted to know, regarding the discrete GPU, whether it blocks or removes other options, like the battery rating (42 Wh vs 54 Wh), the available RAM or M.2 slots, or anything else.

The second question regards an M.2 drive. Some of them come with a heatsink attached, and some without. The larger capacity ones are recommended to have a heatsink, and inside a laptop, where airflow and cooling never seems to be enough, and in this case, where the 28w i7-1390p CPU is installed, there is even more heat. Likewise, the discrete GPU adds heat as well.

Is there clearance for a heatsink inside the case ?

Is there a published/known amount (in mm) ?

Is it a problem to use the M.2 SSD without a heatsink in spite of the manufacturers recommendation ?

All technically informed responses are welcome
TIA