Hi,
We have read and understand the requirements you have posted and we're very interested in providing a solution.
We need to read the external DB and the location. We can add an API script to the external DB location and will create a script to the WordPress website area to fetch the data from External DB to update/add the data.
We are a professional development company, we have expertise in PHP, MySQL, .NET, MsSQL, jQuery, Wordpress, HTML etc. and have more than 1600 jobs under our belt.
Please have a look at our freelancer portfolio.
If you like what you see and if our proposal and quote fits within your budget then please PMB me your response and we will take it on from there.
Regards
-Sam