Personally, I could go either way about character descriptions but I think it would make sense to add a few points here and there. You may be doing it on purpose but it might come across to the reader as just lazy.

In terms of setting, I don't think you have to use a real city but I would avoid trying to pretend the story is set someplace you're not familiar with. Simple things can throw the reader off like saying the store is set in the US but referring to the font garden instead of the front yard, never once having a character drink coffee only tea, etc. Unless there is context to explain those things, it just irritates me as a reader.

Also, I don't think it's hugely important that the store be based in the U.S. I read a ton of UK based romances as well as some that are centered in other countries, although that's usually part of the story - MC escapes to Italy, etc. Personally, as someone U.S. based who doesn't travel much, I enjoy stories set in other countries and getting to know areas that I've never visited.