1) Answer = Uncle

Therefore, Grandmothers son is your mother's brother = Uncle 

2)Answer = Cousin (who is a girl)

Fathers mother = Grandmother.

Therefore, Grandmothers daughter = Fathers sister (or Auntie)

Therefore, your Aunt has a son, and the son has a sister (so the Aunt has a son and daughter) = A cousin (a girl)

I guess it's:

1. your uncle

2. your cousin

I hate these structures. To help, grab some paper and something to write with and just make a chart. Shame i can't upload pics on here so I could break it down for you guys.