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Most of the time, Alamo and National pull from the same fleet of cars, so the cars you'll find within each class will be very similar between the two brands. That said, as the top-tier brand, National will tend to collect the nicer and/or lower-mileage cars.
National does not have kiosks. However, if you are a member of National's Emerald Club, you can skip the counter completely and just walk directly to the lane of cars matching the kind you have reserved (including accessing the Emerald Aisle if you've reserved at least a midsize), show your license at the exit gate, and be on your way. It's free to join, so absolutely no reason not to.
There are very few toll roads in California. The bridges in the Bay Area are tolled, and some (very few) expressways in the Los Angeles area are tolled. In SoCal (L.A. and San Diego), single-occupant vehicles with a toll transponder can access some (but not many) High-Occupancy Vehicle (carpool) lanes for a fee. Unless you plan on driving across a lot of bridges in the Bay Area or need access to these lanes in SoCal, the toll plan is not necessary. And if you do plan on using these toll roads, just stop at any participating merchant (check the FasTrak authority for your destination area--
try this Google search for starters--and pick up a transponder yourself. Typical costs are $25 for the transponder, but that includes $20 of toll credit, so the net cost of the transponder is only $5, assuming you plan on using $20 worth of tolls.
You may be able to avoid using a transponder altogether, although some bridges (like the Golden Gate) have gone to 100% electronic tolling (you can't pay cash).
You may have more luck getting a comprehensive answer if you do two things: post your specific destination area and route of travel and do so in
the California destination forum.