SSD in 2009-2011 13" MBP - what slot?

[ExnomenDei]

I'm reading some mixed comments on, if you decide to use an SSD + HDD option (remove superdrive), what slot you're supposed to put the SSD in. Obviously, I want to use an SSD to boot if I go this route, so it has to work fully like that (including sleep), and I read a few comments on it not working with the optical drive's connection. However, I also read there is no safety for the HDD when you put it in the optical drive's bay. So, what works and what doesn't? Also, does model matter here, since I have a 2009 13" MBP and am thinking of getting a 2011 13" model?