I agree with the changing them at home until you're confident. Do not rely on plugs to work when the shit hits the fan, or you'll be very cold/miserable; be confident with pulling a tire, installing a boot/tube, and get moving. [incidentally, this is also a good time to go over your tires and see if you've got anything stuck in them, since you'll immediately give yourself a flat if you put a tube in]
I also am a fan of Dynaplug over regular strips. The Darts are fine, but they rely on sealant to work (ie: they aren't going to fix a hole/tear without it). Plugs make a permanent repair if that is important to you. Also, Dunaplugs come in 3 different tip types/2 plug sizes. I stay away from the sharp pointed ones (they make rounded points, but these are easy to modify yourself if you already have/can't get them), but danger from getting a catastrophic flat and damaging the rim is over-rated, imo.
In the cold times, I carry a couple of packs of warmers with me. I'll still be cold, but whatevs. I usually figure on ~5 minutes to change stuff, and that's usually the amount of time you get from high intensity work to standing still before you start getting cold.