Welcome to the forums!!! If your temps are going to be that cold, if you have a shed or a room you can keep the bees in, that's heated to say 60f or greater I would do this until it warms. You don't want to install them and feed sugar water in those temps, they can freeze to death.
If you have to install them, feed them candy or fondant: http://www.bushfarms.com/beesfeeding.htm#feeding
Depends on how cold 'cold' is. We install all the time in the 40's, we have to, if we waited for warm weather we'd be waiting til mid-May some years!
It was around 45 on Sunday when we installed, it was a quick, fairly calm install, the bees were too cold to get too riled up. We sprayed them with sugar water and poured them in!
Obviously if it were colder than 40, or windy and rainy, we'd hold them for a few days.