Do we still receive support if we buy-out our Apps for full ownership?

Support will be limited as you will have the capability and permission to modify the code or replace each App. Any changes to the code, any corrections (such as to correct any unwanted changes your developers produced), or updates would be at your cost as soon as you own the Apps. 

You would still be able to control all your Apps via the Media Cloud in the same way, provided your developers aren't removing the Lightcast feeds.