Your data is a very sensitive part for your site.  The backup of your data is crucial.   Usually your hosting provider makes easy.

But you are still responsible to download the information to make sure that your data is with you.

The data is the heart of your Internet business.  This includes your business information to your customers in the web and your customers information and feedback.

A database system is the easiest way to handle large amount of data in the web.

There are some main database servers and all of them could be ideal for you.  One point to consider when picking one is which one your developer approve and is willing to work with.  Another thing is the speed, the amount of data and how easy is to back it up.