Hey Aheywoo,
As far as I know, we don't give any access to the DB.
As for the REST API, you can control the size of a page using the page_size parameter (our default maximum is 1000). You can see this in the pagination section of the RestApi Response Documentation. We don't currently do any throttling as far as I know, see this post for a discussion on throttling.
There are a few ways to see messages ordered by date, you can take a look at the Recent Posts call as an example of this. Let me know if this call doesn't meet your needs and I will provide alternatives.
Hope this helps,
Yuri