Did a search of the forums and couldn't find an answer, so hoping someone here with this setup can help me out.

I recently lost my Cateye Astale 8 headunit. I have a Garmin Forerunner 410 that I use for running and want to also use it on the bike. While it does have a cycling mode that shows are the normal stuff (speed, distance, pace, HR, etc) I really miss having a cadence sensor. I tend to overspin myself and tire quickly if I don't have a reading right in front of me. The GSC 10 from Garmin will pair with the 410, but I have a couple of questions that I can't seem to find any definitive answer to:

1) Which takes precedence, the GPS enabled speed from the watch, or the calculated speed from the magnet/sensor combo on the rear tire? I do mainly road riding with few obstructions so the GPS is quite accurate and don't particularly want/need to speed sensor for my distance and speed and such.

2) I've read conflicting reports on if cadence will show on the 410 unit while in use. It looks like it will do the data dump to the Garmin site for certain, but I really need it to show on the watch face, can anybody confirm if it will do this or not?

Yes, I could buy another Astrale 8 or similar, but for ~$35 the GSC 10 looks like a good unit with better bang for the buck and will reduce the number of things on my handlebars by 1.l