Each version of Pressflow is API-compatible with the same major Drupal version. For example, Pressflow 6 is compatible with all Drupal 6 modules. Pressflow 6 also integrates the SimpleTest system from Drupal 7 and the CDN support patch.
cookie_cache_bypass.module and path_alias_cache.module are not mentioned anywhere. There should probably be an explanation for them and when to use them.
cookie_cache_bypass.module and path_alias_cache.module are not mentioned anywhere. There should probably be an explanation for them and when to use them.