I had some additional Questions:

1) They will not use any kind of modded car, as far as getting in themselves and riding along? As I plan to try to use a modded UAZ cargo truck as a mobile base.

2) Does Hydrocraft disrupt the AI as well as any issues with mods that changed the catagory/name of items? (I use these for ease of sorting things)

3) Will the "wild" survivors who come to say hi automatically join you or do I have to right click and invite? I would prefer the latter as I don't want to amass a huge group to keep food needs manageable.

Holo to answer your second question: That was probably a raiding party, you can disable them in the in game options for the mod. There are options to wait X days before they are able to spawn then options for X days between raids. You can set these to "Never"

To answer your first question: Damaging your group members is disabled even with PvP turned on. You may just need to call the person over and then tell them to leave through a right click menu.