Last I checked the importer worked fine. Set up a small blog with garbage content and import it to test.
There's no theme that works specifically better for imported blogpost blogs that I'm aware of. You can search and see if there's a WP equivalent of the theme you're using for blogpost, but you're almost certainly fine to just choose whatever theme you want from the free ones.
themeforest (affiliate link) has very affordable themes, with several designed specifically for storefronts like the one you're dealing with. They tend to be very user-friendly and don't ever require the users to touch code to make big changes in design and layout.
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