Have 26 Star 2 door R. It has a lock on the outer passenger side door below the handle, but not the driver's door. I don't have a key for the door, the lock is different than the ignition, and am fearful of accidentally locking the car doors (and don't know how) without a key to re-enter. Any advise? Thanks!

If you remove the lock portion and take it to any locksmith worth his salt, he should be able to make you a key for it.

Can you lock the car doors (accidentally or intentionally) from inside the car without a key?

Usually you can lock all the doors, with the exception of the passenger's door, without using a key. The most common method is to move the inside door handle in the opposite way to that of opening the door. This effectively keeps the outside door handle from moving. Most passenger cars of the period had the lock on the passengers side. You locked this door while standing on the sidewalk, away from the traffic.