Re: Painting foundation

"Probably", unless it's approximating new construction -- in which case, you've got 'green concrete' issues to deal with, instead.
A medium-potent detergent solution, scrubbing with a stiff bristle 'scrub brush' (the objective being to loosen any 'ground in' crud), followed by a *thorough* rinsing. After all this, you'll need to let it dry thoroughly, before applying the 'finish' -- absolute minimum a couple of days.
As for priming first, "read and follow label directions" for the "finish" product you intend to use applies.

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