For question #2, you could get a Rick Oleson screen with pattern 135W:
for #1, I remember reading someone going into depth on a reusable leader to conserve film, but for the life of me I can't remember. If you have a backing paper, I'd load it, advance the the first frame, then open the back and measure the distance, and use that measurement, minus an inch or two.
BrightScreen MPD – Bright Screen
The BrightScreen MPD has a 6mm diagonal split image set in a microprism collar. The MPD screen is best with eye level finders, geometric subjects such as architecture, and for general photography.
for #1, I remember reading someone going into depth on a reusable leader to conserve film, but for the life of me I can't remember. If you have a backing paper, I'd load it, advance the the first frame, then open the back and measure the distance, and use that measurement, minus an inch or two.