How can I export my Comcast address book to my iPad?
Follow this guide to export your contacts from Comcast in the vCard format (VCF): http://www.watchingthenet.com/export-address-book-contacts-from-comcast-webmail.html

Then, email the vCard file to yourself. Open that email on your iPad and download the attachment. Now you will have your Comcast contacts on your iPad.