Carolsue,
Welcome to Cruise Review & Princess

I hope you will enjoy your Mexican cruise on the Dawn.
There is an Internet Cafe on the ship. They usually quote a price of 35 cents/minute.
Sometimes the connection occurs quickly & other times it seems to take forever, but, at least you do have access, right?
Usually the center is open 24 hrs/day. Again, sometimes they may have trouble to get a connection.
Pillows - Usually you will have at least 4 per cabin. Let me try to think I do not recall them being feather pillows. This can vary ship to ship. Of course you can ask for more pillows.
At home I use a special pillow, but, usually can manage with what they give me. But, you can certainly bring your own pillow.
Not sure on the parking in San Fran. I had to fly in.
I do know that there is parking available.
Perhaps someone else can supply you with this info.
Ask away with questions, that is what the board is for.
Enjoy your cruise

Cathy