Which Anti-Spam Plugins To Install?

Aloha! I am not allowing blog creation accounts into my network at this time (have blog subjects already created). However, I would like to allow free members in for certain interactions such as the Q&A and Community functions (not using BuddyPress).

I installed the Combo Anti-Spam pack, and when I was setting up the Q&A plugin, I noticed that another anti-spam plugin was recommended - Stop Spammer Registrations Plugin. Can I add this plugin on top of the combo pack without causing things to go haywire?

Also, with all these anti-spam tools available from wpmudev, I have yet to activate akismet. Should I go ahead and activate that also in addition to all of the above?

Since I'm not allowing blog creation accounts at this time, I have not installed the anti-splog plugin... phew! All these anti this and that.... lol