Jerry,

You have been given good advice here. Between the 2 you mentioned, for an "all around" sander, as mentioned, my choice would be the 150/5. That extra 2 mm orbit makes sanding in grits below 120 more efficient than the 150/3. Most any shop vac would work, perhaps not as well as the Festool because of/with adjustable suction, but some folks have managed to create a sleeve for the Fein vac that allows the suction to be adjusted. The Fin vacs, BTW are excellents vacs.
There is a 10% discount on the price of the vac when bought together with the sander - that may or may not be enough for you to get that "package". But any vac you do get; I would make sure it had good filtration and tool actuation.

Bob