First thing you do is break the sack. Second thing you need to do is suction out the pup's nose and mouth and get it breathing. Then once the pup is breathing well, then you tie the cord for a couple minutes and cut it.
You can let mom eat one or two placentas but I wouldn't let her eat any more or she may get diarehea.
I will always do everything for the mom's, it is too risky not to. I have heard of the mom's chewing the cord to short and endangering the pup's life. Destiny would have if I had not cut it myself.
Here is a good site you may want to look over, it has a ton of information on the whole birthing process and the do's and don'ts.
http://www.debbiejensen.com
Also make sure you count all the placentas, this is very important. Because if you are missing a placenta it may still be in the mother and you will need to take her to the vet to get an oxytocin (sp?) shot to clean her out.
Good luck. Can't wait to see the babies!!