Are there any multiple companion glitches? Similar to the one from F3, where if you killed dogmeat you got an extra companion slot? I want two humanoid companions, to make a sort of "strike team".

I don't know about any glitches but if you're on a PC, you can get the Unlimited Companions mod. I use it and for this game, I'm traveling with Boone, ED-E, Cass and Raul. Sometimes 4 is too many but we're nearing the end so I'm going to pick up Rex and Lily for the final battle since I didn't have Arcade and his friends with me this time out. I first got the game for my PS3 and then wanted to learn to mod so I got the PC version too. Maybe someone else can help if you're on a console. Good luck...it's a lot of fun and companions are my favorite thing in the game.