Garmin GSC10 Cadence sensor

Yes, you will get speed and distance since the pickup comes from a magnet on the back wheel.

This is actually why I bought my GSC 10... works like a charm.

another nice feature of gsc10/garmin is that if you've used it outside before using it inside, it will automatically calculate your wheel circumference.  

Yup, and if you haven't gone outside (or forgot, like I often do), then you can set the wheel size manually and also save it for individual bikes.

Also, just as a note - remember that distances on indoor trainers are sorta 'fudgy'.  That's because depending on the gear ratios you use you can easily spin out lots of miles with little effort, or spin out very few miles with a heck of an effort.

Yes.

Love it.

Just hold down the mode button, and select "Indoor use".