What surprises me is that you ask these questions at the 12th hour, youre not prepared properly for the whelping!! You had two months to research and collect the information and needed whelping kit yet you still search for answers to some of the most basic questions.
I would suggest you have a vet on call 24-7 to assist you in the whelping Your lack of knowledge can indeed indanger the life of your little gal and her off spring!!!
I suggest you read this
http://www.debbiejensen.com/whelping_day_photos.html
and google "pregnant bitch" read all you can and search for someone to help you! Get your vets personal cell or home number so you can call anytime or locate an emergency vet near you and keep that name taped to the phone!!
Even we seasoned breeders hope for the best in every whelping but PREPARE for the worst!