anti-splog, protect content and akismet

1 - anti-splog is strictly for blog registration only and does not prevent comment spam ?
2 - if using gravity forms "user registration" add-on which has a feature to replace the standard WordPress registration page, does this prevent/limit "anti-splog" from working ?
3 - Kismet plays/pairs well with anti-splog ?
4 - if "Protected Content" is protecting pages, would this help prevent spam ?