2 are minimum but it helps to have more in case 1 wanders off or is killed.
Yes its accurate.
You don't know exactly where its going to be, there was a thread that explained a lot on bases, search best base, or something like that.
Yes it does but buying a base from Redding might not place it near Redding, instead it could be by Broken Hills or Vault City, once again that thread.
On your example no.
Also if you are going to buy a base from unprotected area be sure to have someone scout it first for pks and have a list of possible Generic Name ###'s ready, make sure you do not let the talk timer run out.