Hi,
The crack in the glass is pretty subtle, just above the lower left corner. Unless one drops the back, that crack isn't going to spread...
It has a simple Graphic (not "Graphlock") back that will accept any standard 4x5 cut film holder. This is for 4x5 cut film holders only. Graflock backs are designed to let you use roll film holders on 4x5 cameras. If that's what you're looking for, this back won't do that. Personally, If I want medium format, I'll carry a medium format camera.
I haven't researched the age of this unit, I bought it used back in 1960 (or so). I used it for landscape photography for a few years, then put it away (other "diversions" called...). If you're thinking of backpacking with a 4x5, monorails are a bit awkward (although, back when I was a younger sprat, I did short backpacks with it.).
This camera's bellows draw is about the same as the popular 4x5 Tachihara field cameras, so useable lens focal lengths are about the same. For landscape photography, 75 to 210 mm lenses are typical, and this camera will do nicely. If you're thinking of doing tabletop and still life photos, the bellows are a bit short (close-up photography requires significant bellows extension).
Hope this helps.
Reinhold