I would also like to ask if 100% in all difficulties will be accounted for and what 100% is

100% is just reaching 100% completion on the file select page from starting a new file. I don't remember how difficulties affect that unfortunately, haven't played the game in a while.

100% requires:

• All levels on easy (including temple) beaten with the stump temple piece
• All levels on normal (including temple) beaten with the stump temple piece and emerald
• All levels on hard (including temple) beaten with ant collected

I'm not sure whether it requires all balls unlocked but if someone wants to check by not getting any golds in easy/normal be my guest