I mocked up the two scenarios, and determined that with the plate inside the stretcher the vise would have a reach of 8 inches, and with it outside the stretcher it would have a reach of 9 inches. I decided that 8 inches was enough, and that the extra inch wasn't worth the extra effort. With the end vise mounted like this, the right edge of the top would have no overhang.
The original design had a height of 35-1/8". Their two-layer top was 1-1/2" thick, so their legs were 33-5/8" long. I want a height of 35", but I'm using a top that's 3" thick. My basement floor is anything but level, so I'm using levelers that are adjustable from 3/4" to 1-1/2". In other words, I want legs that are around 31-3/4" long. (If you're not using levelers, your legs need precise lengths. The levelers give about 3/4" of adjustment, so precision is less necessary.
While a strict figure for the bench’s weight capacity is not available, a quick browse through their other stand and bench products shows a general weight capacity well above most other brands. As such, while we cannot say for certain that this bench provides the best weight capacity, it is more than likely that it the capacity is similar to the other products in the catalog.