Yes if the breast feeding continues for whole day and whole night or it was 14 times continuously.
The woman then becomes breast feeding mother.أم رضاعية
No, it is not permissible for any one to cause distance or cut relations between relatives. It is a major sin which is mentioned in Quran with a curse from Allah on the person cuts relations with relatives.( Sura 47, verse 22 and 23). Even if her father in law is oppressive, he remains related to her child and depriving him from seeing his grand son is a major sin. The Prophet Muhammad (SAWA) did not stop his wife Um Habeebah from seeing her father Abu Sofyan who was one of worst enemies of the Prophet. He allowed her to receive her father in the house of the Prophet.
It depends on the way of using the vaccine.
If such vaccine is to be taken orally, it will Haraam to consume it.
But if it is not taken orally but injected in the body or dropped in the nose with out letting it go inside the stomach, then it will be allowed.
After completely removing the actual Najasat, the Najis couch or bed or item must be washed with water, one time with Kurr water (big quantity or current water) or three times with small quantity of water/