1) A-If you do not know then there is no objection it but if you know that there is some or all are haram food in it then not allowed to deliver.
2) A- Do Amr bil Maroof and Nahi Anil Munkar which is wajib.Attend the majlis In’Sha’Allah it will help to guide them only do one thing do not sit in mix gathering.
3) A-If sitting with him is to help,assist or encourage in disobedience of Allah then not.
4) A-if it belong to a shia who is not disobeying Allah in public and he is not giving importance to Halal and haram then refrain to visit but we are not allowed to investigate about anyone.
5) A- if they are Muslim you don’t need to investigate.
6) A- Anyone who does not believe in necessity of religion like usool e deen and namaz, Roza and haj etc they are najis. There is not matter of good and bad matter of belief.
7) A-They believe in necessity of religion and they are practicing and they are Paak(pure).