How long should the PHB to be and how should those pages be used?
I think the ~300 page PBH is too long. 200 pages would be better, IMO:
Core - 10 pages (RPGs, Abilities, checks, character creation)
Races - 10 pages (4-10 races)
Classes - 20 pages (4-10 classes)
Kits/Themes - 20 pages (class...