I wouldn't say it's a phobia type fear, I'd say it's more paranoia. That out of hundreds of cars, I'm going to get the maniac that's so 'late' for work that he will run over me on my way to work. Logically, I know it's unlikely. But I'm paranoid. Luckily, I don't have my bike yet, so I have time to get used to it. I do know that I see bikers literally everywhere around here, especially on Saturdays, so hopefully the drivers are no stranger to sharing the street.
As far as a biking buddy, I barely know anyone at all up here, let alone another biker. ^^; I just moved up here. My few friends complain about the bikers slowing their morning/evening drives to work. So I don't know where I'm going to find a riding buddy, especially since no one else at my work rides.
I'll probably get a mirror after I've broken into the biking scene a little. I know it seems backwards, but when I'm first starting on something, I don't trust mirrors as much as I trust my eyes. And while I haven't been driving, I have been my mother's navigator for ages. Which means checking her right hand mirrors, lanes, exits, etc. So I'm not a total stranger to the road, it's just that I only know the theory.