It is difficult to test for every situation since everyone's system specs are different. The product was tested on multiple platforms and worked there.
You should be able to run Surveyor multiple times without having to restart Dreamweaver. I'm not sure why you are unable to. Try running Surveyor from different access points (Insert menu, Insert Bar, WebAssist Site Tools).
As for getting .css files in the sitemap, you can specify what file extensions that will be included in the sitemap. Just add .css file extension to that list and your sitemap will have .css files included.