No, you don't have to be at all - it just support the likelihood of an Author not making such a choice by accident.
I definitely hope for at least three seasons.
I see a large number of possibilities here. One is that Alpha actually has an alter-ego. She thinks she learns fast - something she's mentioned a few times in episode 2 - but she actually shares physical memories with her alter ego. She may also be the one who killed the other people; she sounded pretty crazy about things being cut up in the episode 1 flashback (remember, I only saw episode 2, so I may be way off-base. Also, both the Dollhouse and Adam may be big bads, or Adam may actually be good - if Echo killed the people when or after Adam left - and the Dollhouse may even become a tool for good, to help people. I haven't given the series that much thought yet, but there is a lot of directions this can go in.
I definitely hope for at least three seasons.