What if the Zav's spit does not actually touch the person but lands on the stick that he is holding?
Rashi: Spit is Metamei the person who touches it and who carries it 1 - together with the clothes he is wearing.
Even if it landed on the stick that he is holding (Sifsei Chachamim) - provided he walks with it or moves it.
How about other liquids that a Zav emits?
Rashi (Shabbos, 14b): All liquids of a Zav that collect before being emitted - such as his urine and his mucus 1 , are Metamei like his spit.
But not his blood.
Fluids of a Zav - why are they Tamei after they separated from him?
Moshav Zekenim citing R. Yehudah ha'Chasid: There is life in a person's limbs, even after they separate from him. Limbs are different than fluids. 1
I do not understand this. If limbs and fluids are the same, there is reason to consider the fluid Tamei, for it is as if it is part of him even after it separated! (PF)