They do not have to be released all at once, but they should be consistent, and not need constant rewrites or clarifications. What is first published should be clear, concise, and unequivocal. There should be room for expansion, and that expansion should be planned. What is printed should have been play-tested. What is printed should be proof-read. PH1 should be a good, solid, book, with basics for many races and classes. If a race book comes out for one race, there should be one for EACH race or origin (a book for all Fey, one for underground dwellers, one for shifters/beastmen, one for monsters). If a class book comes out, there should be one for each class or class type (martial power/arcane power/divine power was a good move for 4e).
All bonuses are typed. Period.
Keep the power sources either even with each other, or just limited.
Feats should make sense.
I don't know the name of the program used for the current online character builder, but it should be abandoned in favor of a much better, faster, and more reliable version.
In fact, the online builder should be tossed in favor of the downloaded version, which should be right the first time, and supported as the game expands.