Another player and myself both have Prime Position and Blind Spot. Do these talents stack with each other?

They both trigger once you (or your allies within short range) are in cover, yes. You don't have to choose between the two effects.

38 minutes ago, Stan Fresh said:

They both trigger once you (or your allies within short range) are in cover, yes. You don't have to choose between the two effects.

The talent Prime positions is a ranked Talent. If we both have one rank does it come accumulative bonus to make the benefit equal to rank to?

Blind-spot is not a rank Talent but if we both have it does the benefit stack?

With both characters having one rank of each talent I'd go with 2 advantages and +2 soak.