Does SJC have a priority PLT security line?
Yes. I've never seen a person enforcing it like most other airports, but everyone seems to respect it. Since many airlines moved from terminal C to A recently, you often need it now too! ^
How does the Admiral's Club compare to others?
It's not a LHR, BOS, or DFW terminal D, but it's still a nice club. The staff there are probably the friendliest I have dealt with at any Admirals Club. I'm not sure how much bias there is from it being the home airport, but others have echoed my opinion.
What would you recommend for lunch or breakfast there?
Gordon Biersch Brewery has a location right on the other side of the security checkpoint. There isn't much else in the way of restaurants unless you want to walk to the Southwest gates at the opposite (south) end of the terminal from the AA gates and Admirals Club.
How far is the Hertz rental from the terminal?
The car rental lot to the terminal is about a 5-minute ride. Terminal A is the first stop. The car rental lot is on the northeast edge of the airport.