I agree with the use of the DAT to prepare your songs for mastering. You then need to decide where to send the DAT (to be mastered). You also need to decide where you will send the finished master for duplication (and determine how many copies you will need). You also need to decide how you will package your CD - re: cover art, etc. etc. (I hope you already have a distribution plan).
I suggest you contact a couple of recording studios in your area and ask for references. Many studio's don't share this info (if they know a great mastering engineer who makes their product sound better than others - why would they share this info?). However, you may get lucky. You could also check with your local music store for references.
Look in the back of any magazine (Recording, EQ, etc) there are dozens of mastering/duplication houses listed (ask for references from others who have used their services and/or copies of their work). Contact the mastering/duplication houses and they can tell you what format they need/prefer and what info they need from you (D/A conversion rates, type of noise reduction used, etc.)
Good luck.