Noun and Pronoun flexion in contemporary English

We know English has only a handfull of verbal flexion forms. But in
modern English the tenses etc. lead to a conjugation (or declination?)
of the subject, as in

he'll go
Peter's going
we've done it

and so on.

Is there a name for this kind of flexion? Would it make sense to call
"he'll" a case of "he"?

Does something like that occur in many languages?

Joachim
.