The bad news is the old TV don't get to upgrade. I, as many others, got stuck with WebOS 1.0. I don't believe the 2015 TV's will get the 3.0 upgrade neither. TV companies are so bad at firmware upgrade. Why don't they just use AndroidTV. Let Google do all the development.
I don't know why you don't have the store if you have WebOS. Perhaps you have to run through the setup again; I think there may be some caveats to the TV turning on the "Store" app?
I am on WebOS2. I am under the impression that the store is installed with WebOS so long as you complete the initial setup.