Easiest way to reinstall store content?

The ebc file bundles in your DCCache are your installed store content. If you move them to a new game folder (or a new computer) then there is nothing to install, if things are working as they should then it's all already there. You would also require your ccmerged file from DCBackup (not the rest of it) in order for premium store items to work.

The dbc file bundles are already installed CC. Any tmp files in there are expendable garbage.

Sims3packs that are in Downloads within the user game folder are those waiting to be installed or those that already have been. There is no need to keep any kind of sims3pack content in there after it has been installed, it is best stored elsewhere.

It's admittedly not a perfect system and some players will find that they do have to rebuild their content collections by reinstalling everything. The only time I faced that myself was when I switched from Origin to Steam for the install platform, but that was at that point to be expected.

I tried again, but nothing showed up in my game when I moved the folder over, so I just reinstalled everything from my purchase history. I own the store, so I had 100 pages of stuff... hopefully I didn't miss anything.