I'm borrowing my friend's 2005 MCS for a few months and would like to know a few things.

Photos:

http://jae-designs.com/MiniStuff/

Does this have a Sirius antenna connector under the front passenger seat? I can't seem to locate it, I've heard it's a yellow wire?

I couldn't get any real good shots but I believe there are Hsport springs on there and definitely an Hsport rear sway bar. It seems it's on the medium setting, is it?

Does this car have a front sway bar? I can't seem to see it without some ramps or a jack.

On the last photo, what is that wire loom supposed to connect to, alarm system? Could I hide a Valentine One or something in there?

 

Most people don't add a front bar, the car comes with one. They add a bigger rear bar to get more oversteer dialed in. Yes, middle setting.

Dunno about the wire loop but most things are wired for stuff even if the option is missing.

 

Can't help you on the Sirius, sorry.
Yes, you have H-sport springs and sway, and the sway is on the middle setting. The hole closest to the end of the bar is the lightest setting, and tightens up as you move inward.
If the wire loom you are holding is in the ceiling at the rear of the MINI, then yes, that is alarm wiring. You can hide anything there that will fit, but as far as power connections, I don't know. Maybe try that question in the electrical or audio/nav sub-forums.

HTH