HHH Giving Tal its Due [dew?]

Given:
When Ashkenazim recite Tefilas Tal on the first Day of Passover the nusach is: Mashiv Haru'ach umorid Hatal

Question 1:

Would it not make sense for those Ashkenazim who continue to say "Morid Hatal" after the first time until Shemini Atzeres use the very same Nusach and say: Mashiv Haru'ach umorid Hatal instead of JUST Morid Hatal? And if not, why not?

Corollary Question 2:
During the Summer, Instead of saying just: V'sein Brachah, why not say: V'sein Tal Livracha [in other words w/o Matar but keeping Tal in the picture?]

Mo'adim Lesimcha
RRW