Bass -> DI -> Interface/Preamp -> Cakewalk
Use the XLR out on the DI, and make sure that the preamp is on (XLR input on the FastTrack). You are using a mic cable between the MXR and the preamp. The DI should be sending a mic level signal, and the preamp should be really happy with that. Avoid running the output of the MXR too hot, as you want to be able to hit 0db with the mic pre gain level set between half and 75% level. These settings are not gospel, they are a basic approach to getting your gain staging fixed. You will find a happy medium where the DI isn't overloading the preamp, and the preamp isn't running so much gain that the noise floor is up in the mix.
Once you have that worked out you can work on tailoring the MXR settings and coming up with a processing solution in cakewalk. Keep it simple. No need for the ME50B (I'm a former user of one and loved it for live work). Start simple. Get a good solid signal recorded and then work with it in post production. Think of it as having a raw bass signal "on tape" that you can always go back to.
Printing compression or effects is best when you have the rest of the process figured out. There are a lot (I'd wager "MOST" of them) of awesome bass tracks that you hear every day that began life as a vanilla DI take.
Good Luck!
