I now use the foot pod with the garmin when I run on the track. It has been pretty accurate for me. I did a 21,100 meter run on the track last year (I was injured and sticking to rubber) and the foot pod measured at ±0.5% accuracy compared to how many laps I did on the track. When I use it for shorter speed workouts, it lets me go back and look at if I was able to maintain a steady cadence and pace throughout the laps or if I was able to accelerate in the intervals or fell apart half way through, even if the distance wasn't perfect, it is still more consistent than the GPS. My results will show that doesn't actually make me any faster, I just like looking at it ;-)

2. I'm fairly confident that it was certified, but even if not I still think the problem is with my FR210 (or more likely, me). I didn't give it enough time to get a good solid fix before starting, and there was a fair degree of tree cover near the turns, so it wasn't as good as it could've been. I noticed a similar problem on my daily runs; if it has a good initial lock, then I get data consistent with my other runs. Otherwise, it'll be a little wonky and cut the turns short even if it's a few miles into the run.

Track >> Garmin, so long as you run the marked official distances per lap, usually the marked inside lane is most accurate. (1 full lap done on the inner lap of a track vs 1 full outer lap track will be pretty different length distances if you don't use the staggered start lines that equalize the distances.)

The curves really screw the Garmin, and because there are so darn many turns on even on a measly one mile track run (8 turns, typically), a tiny GPS error quickly multiples to become a very significant error. On a straight out and back course with good signal, my Garmin is 99% accurate and reproducible. On a track with same good GPS quality, it's not unusual for me to see 10% distance variation, and you can look at the GPS traces which show the actually tracing errors.