Please disable automatic priority calculation and define a static priority for posts.
No, if you edit/publish/delete a post, your sitemap is automatically regenerated
No, only if you want to. Default values should be ok!
This version works with WordPress 2.1 and better. If you're using an older version, please check the Google Sitemaps Plugin Homepage for the legacy releases. There is a working release for every WordPress version since 1.5
If you get permission errors, make sure that the script has the right to overwrite the sitemap.xml and sitemap.xml.gz files. Try to create the sitemap.xml resp. sitemap.xml.gz at manually and upload them with a ftp program and set the rights with CHMOD to 666 (or 777 if 666 still doesn't work). Then restart sitemap generation on the administration page. A good tutorial for changing file permissions can be found on the WordPress Codex and at stadtaus.com.
Most of the plugin options are described at the plugin homepage as well as the dedicated Google Sitemap FAQ
Please post your question at the WordPress support forum and tag your post with "google-sitemap-generator".
The changelog is maintained on here




