They are a scam

Partner with someone local rather than paying 10k to a shady company who goes from town to town scamming people. 

For what it's worth, I would advise you to be extremely diligent about purchasing replacement windows, and not fall for the dozens of scams purported by that particular industry.

Any recommendations or problems you encountered along the way?

The person you encountered could be a visiting friend or relative who had just stepped out for a few minutes and your tenant passed them keys.That said, as Jeff Beard alludes, you might introduce yourself and just keep an eye to see if this visitor stays beyond the "guest" period of your lease.  

3) What are the biggest hurdles we may encounter during the refinance aspect?

Our condo has had no issues in the past 15+ years [since converted from apartment] even with torrential downpours; the only drawback I've personally encountered is the change in temperature during the seasons.

I shut down every one and have educated hundreds of owners how not to get scammed.

What were the upsides/downsides you encountered?

Just my two cents, but for safety's sake, I would verify that the notice was genuine first by calling the municipal authority/agency responsible for generating such violations and notices to confirm that the notice was NOT a scam.