Last time I looked the MS Store was just a sad catalogue of shovelware. Has it improved?
Depends how long ago that was. When it first came out you could only upload UWP apps and hardly anyone used it, in recent years they've relaxed it a lot (you can just publish EXEs and MSIs now, fees reduced/abolished) and I see a lot more open-source projects using it now.
Yes but it's free and easy to link customers there. They don't have to interact with the store outside of your product's listing.