question

There's a very specific reason we don't provide arbitrary query into data tables in our primary service: it's one of the top ways that titles have torpedoed themselves, across all shipped mass-market online games. Our primary service is shared across many titles, so a single title that has a bad query would impact everyone. That's not something we can tolerate, so instead we provide accessors for all the various data elements in our system, each optimized for the data in question. Beyond that, if you have a need for arbitrary query, we can certainly work with you on a contract for a private cluster instance of PlayFab, so that you have a version of our service which is exclusive to your titles.

For your other questions:

• Bundles: Specifically, this would be "items that have other items attached to them". Think of it as "buy A, get B for free". So the items in the bundle are all added to the player's inventory when the primary item is added.
• Containers: Not the same as a bundle. When a container is added to a player's inventory, it's one item. It only delivers its contents to the player inventory when it is opened (via UnlockContainer), and you can define a Key item for a container, so that the player has to have the Key to open it. The Key and the Container each have their remaining uses decremented by one when used, so that they are removed from the player's inventory when they're used up.
• Store: This is a subset of items from the catalog. This can be used a few different ways, including subsets which are specific to character classes (so that you don't have to download everything), and "sale" stores for specific events, like a holiday sale period. You can also define an item which normally has no price (meaning it can normally only be added to the player inventory via a Grant operation) as having a price, which allows you to sell items that can't be purchased otherwise - this is a good technique for draining virtual currencies out of your game, if you find that players are hoarding them.