1) I have read the kafir is Najis but when I’m in wudu and I touch a kafir will my Wudu become invalid/batil?

2) What if the kafir is wet or dry? Now, let’s say someone I know is a non believer touched my clothing or my body, now it’s najis. But I had wudu, I know my wudhu is safe (because the sweat of non believers does not invalidate wudu but is najis) but can I pray in this state where a part of my body has the sweat of disbeliever, that part that has the sweat has become dry? can I pray in this state and is my prayer valid without having to wash the part where the disbeliever has touched me with a wet hand?

1- No your wudhu does not get invalidated.

2- If the kafir is dry, your hand does not become najes.

3- If a non-Kitabi kafir touched your clothes with wet hands or their sweat got on your clothes, you cannot pray with those clothes. You must wash that part of the clothes or change them.