I found some useful links below for answering my questions, ironically in a dead (but very informative) comment from johnvak01. tl;dr: old school versions appl

I found some useful links below for answering my questions, ironically in a dead (but very informative) comment from johnvak01. tl;dr: old school versions apply clarifications and enhancements to the original B/X rules for smoother gameplay, some add additional content, and many people want to avoid paying anything to WotC