Could your wife help to wrangle them? As for chicks of that age being moved out of the brooder: my chicks are brooded outside with MHP, and wean themselves off heat at 4 - 5 weeks of age with night time temps going down to 30's. Cold is not the issue. If you are able to use the tarp to keep the driving rain off them, that will help. You may need to make some adaptations b/c chickens should have 4 s.f. of open space in the coop and 10 s.f. of space in the run per bird.
You'll do fine, there is a learning curve, for sure.
You'll do fine, there is a learning curve, for sure.