A combo box by definition is somewhere you can either type or pick from a list. It's a standard control used in countless apps, on any operating system. You can check if it's possible simply by clicking in the text box. And that's what a featured tag means: one that's suggested as an option.
And yes, the free-form search box looks at titles and short descriptions, not tags. So searching for "banana" will return games that have the word banana in one of those fields, which isn't the same thing.
Bugs are another story.