OK, I found the windows easily, but it took a bit to extricate them from where they were set down over a year ago...
The 2 that hold the lower channel to the frame are not bolts. They have round heads, so I suspect the pic is a general depiction of a fastener. They are 12X24 thread and 1/2" long.
The small screw at the top is a common one I see for things like this, but are rather specialized. The head is countersunk and small and the threads are more like a sheetmetal count, as they seem to be 17 TPI. The 16 gauge is just a little too wide. The length is about 5/16".