No, unfortunately no instant return mirror, but no doubt that would complicate the mechanism quite a bit. You raise the mirror when you depress the shutter lever (or you can drop it back down if you let up on it), then the focal plane fires when you go all the way to the lever's end travel.....

Quite dependable. One of my bodies has been fired 37,674 times (it has a counter) and still works perfectly. That one was portrait camera used for many many years on the streets of Stuttgart. The owner would take your photo then return with the print.