yes, frost will not hurt the flowers but if the plant has been killed by frost you'll want to get it harvested asap.

around 45-50 the plant will slow down its growth and ripening and much colder than that tends to make it go dormant. if you're getting temps in that range you should be watching them very closely...after a couple weeks or so of no growth you might as well bring them in. and pay close attention to your long range forecasts...indian summers can bring on a growth spurt at the very end!

good luck