It is a fairly comprehensive list of what contacts you can earn in missions play.
But yes, you are allowed to start with them if you choose, if you do, you have to purchase them at their established connection rating, any leftover contact points may be spent on loyalty to a max of 4 in most cases, there is an older contacts PDF that had different loyalty max for some of the contacts but I don't remember where to find it, and as memory serves, you couldn't hit the max at start after buying the required connection rating anyways.
You may also start with your own contacts, as detailed as you'd like, but anything they do in their fields of expertise will still base their die pool on Connection x 2 + loyalty.