I suspect that the single biggest factor towards deterring spam on the Paragon Wiki (and OuroPortol) is that we do not allow users to register on the wiki itself; instead, they have to register at the Titan Network. That alone may well foil all automated spammers. I bet the little spam we do get is manually done.
To answer your question: "Is there also a way so that a new member can not do anything until we have recieved an email and "activated" or "unlocked" the account for their use?" Sort of. You'll need to break this up into two parts: notification (by email, which that extension you linked to handles) and activation.
For activation, you'll have to
reconfigure user rights and add a new group for your "activated" users. I haven't tested this, but here's a sense for what I would add to the LocalSettings.php file:
# Disable editing and uploading for non-activated users
$wgGroupPermissions['user']['edit'] = false;
$wgGroupPermissions['user']['upload'] = false;
# Allow editing and uploading for activated users
$wgGroupPermissions['activated']['edit'] = true;
$wgGroupPermissions['activated']['upload'] = true;
Once you've done that, you can then go to
Special:UserRights to manually add users to the "activated" group and activate their accounts.
One last recommendation: Make sure you keep your Mediawiki installation up to date. If you don't, then the spammers will use known exploits (that have been fixed in more recent versions) to spam you. Sometimes upgrading alone will cut back on spam. Your wiki's
current version is 1.14.0; the most recent version released is 1.16.0.