Make sure to have non-evil fame with the Brother hood of Steel or NCR Complete You can Depend on Me and convince her to sell Cassidy Caravan
Free him during the mission Crazy, Crazy, Crazy Discover that Jeannie May Crawford sold Boone's wife into slavery by lockpicking the floor safe Gained from 75 Speech or flirt with him (Confirmed Bachelor perk) If you choose to listen to mister house, you can even get a base of operation in the Lucky 38)
You can have one humanoid (Raul, Arcade, Boone, Veronica, Cass, Lilly) and one non-human (Ed-e, Rex) at a time. Not only can they fight, but can carry items and some time make quests easier. Throughout your journey you can find allies that are willing to join you in your quests and aid support.
