The sub control is not openly visible, and you will completely forget that it is there. The install is very clean. The bass slider control has direct effects on the bass response, including the sub, although you will likely keep it at 0.
What he said. If you didn't know what it was, you'd think it was part of the seat controls package. My sub control knob is just forward of the seat's lumbar control. You can reach it easily, yet it's completely unobtrusive.
Also as above, I've left my bass setting at zero.
Once you get your Reus upgrade, try a lossless* "Giorgio by Moroder" by Daft Punk, starting at 1:50, for a good, bass-calibrating (and everything else) bit of merriment.