Felix,

Yeah, the Hathi Trust site is very useful. Just wish more of the stuff was on Google Books — it's a lot easier to download a book in its entirety rather than having to do it page by page. (Google is a partner in the Hathi Trust with a number of major U.S. research libraries.)

You don't order microfilm from NARA by PG number, you order it by microfilm roll.

I have 73 total rolls of KTBs, most of which I bought back when they were much cheaper. I have T0122 roll 32, I have some images from roll 23 that someone sent me some years ago so I never invested in that roll.

Best wishes,
Michael