Which foods are part of the Protein group and the Vegetable
group?

Seafood, bean, but are part of the protein group and vegetable group.

The person who utilize the progression principle will keep adding the difficulty of the exercise that he's doing, while the person who does not, will only stay stagnant.  the person that utilize progression principle, will get a stronger endurance because now his body is conditioned to do harsher routines.{the answer was already on verified)

Little kids are eat dirt all the time so im sure you are fine