So mysz is feminine despite ending in a consonant?

I somehow managed to remember that mysz is feminine. I just can't explain how.

Czarny chleb i czarna kawa!!

Czy są czarne myszy? Nigdy nie widzałem.

Why is the verb ending pije and not piję? Also if you are starting the sentence would you write Pije wode, or Piję wode?

One correct translation could also be: The black mouse drinks water, since structures of polish and english are different, starting with articles but also the use and meaning of used conjugation form of verbs (time).