Shawnie,
We faced some of these same obstacles when we started our program. One suggestion I would give you is to have your grads complete an alumni profile on your website, giving you all their updated personal information, which you can then enter into your database. You certainly can get the word out via email and social media, but you will be amazed at how "they find you"! If you provide a link off your school's main site, many will find you that way. I would not let the fact that you have out of date records keep you from getting started. You can update as you go - as they come to you and provide their updated info.
June