(1) If husband and wife kiss (mouth to mouth) during fasting, does this break the fast? (2) If kiss involves swallowing each other's spit, does this break the fast? (3) If after kissing, wife becomes wet, does she need to take ghusl?

AAWW

1-      Mutual kissing between spouses does not invalidate fasting unless it involves swallowing the other party’s saliva or spit.

2-      If kissing entailed wetness with the meaning of reaching orgasm and ejaculation, then the whole fasting is void! And whether for the husband or for the wife. But if you mean some vaginal discharge or prostatic fluid from the husband, then the fasting is still valid, and washing the privates and the  respective contaminated clothes is what is required.