I concur with Besk that the Speed Graphic looks like a nice one. If you wanna learn more about the details try graflex.org.
I've spent a little bit of time with that sort of gear. In normal use one typically only uses the front shutter (keeping the rear shutter always open). Fwiw looks like you have the focusing rail sticking way too far out. The normal method is to open the camera then wiggle the front assy onto the rail (use that little bar, with the big hole in it, between your thumb and index finger). Once on the rail slide the front assy forward on the rail until it hits some preset "stops." Then push the bar to the side, locking the front assy onto the focusing rail.
At this point the focusing should be synchronized with the camera's rangefinder. Meaning that in order to focus (on a normal subject) you can just look through the rangefinder and turn the focus knob(s) until the two images line up with each other. No need to use the ground glass.
In use, you (at least I) would typically carry the camera around by the flashgun. When ready to take a photo insert a fresh (loaded but unused) film holder and cock the front shutter (remember, keeping the rear shutter always open). (You should already have the lens aperture and shutter speed properly set.) Next, pull the darkslide out of the film holder (Note that film holders have 2 sides; each side has its own piece of film AND darkslide.) Focus the lens, preferably using the rangefinder, then switch your eye to the little rectangular viewfinder; frame the shot ... and finally, trip the shutter. Reinsert the darkslide and remove the film holder. Put it somewhere safe so you don't accidentally reuse it, or whatever.
Regarding how to trip the shutter... that cylindrical thing near the lens is an electrical solenoid for tripping the shutter. If you have the flashgun connected (a cable between the flashgun and that connector in the side of the camera) then you can fire the shutter via that button on the flashgun. This is how I would generally do it - the flashgun makes a nice handle and the button is a convenient way to trip the shutter. If you wanted to use a flashbulb just insert it into the flashgun and you're ready to go. You just press the same button.
I have no idea of the value. Gotta find the right person I guess. (I already have a couple of similar that I already never use.)