[Ron Ramirez]

Here's my answer to your question #5:

3.75 meg isn't too bad, but I believe I would go with the original value of 2 meg.

Back when I was more into 1920s three dial battery sets, I found that the "sweet spot" for grid leaks was 2 meg. With a 2 meg grid leak I would always obtain the best reception and the most signals. This also held true for Philco models 80 and 84, even though they originally used a 4 meg grid leak.

Again, that was my experience - YMMV.