By the sound of it you don't actually need a database app.
Firstly you appear to need an app to keep control of all your contacts and Apple Macs have such an App called Contacts, which I believe is free on all models. Contacts has the capability of recording a reasonable amount of information and is easy to work with.
Next, having stored all of the contacts, you appear to need to send them all, or a selection of them, a news letter or something similar, which presumably you could prepare on a word processor that you may already have, and then mail merge those newsletters with details from your Contacts app.
If I have over simplified your requirements I am sorry but going down the road of setting up a database could be quite expensive and they are not necessarily the easiest of programs to work with.