Comment moderation

I am using a plugin (dwqa) that overrides wordpress' Settings->Discussion options (eg: I select "Comment author must have a previously approved comment" but comments are approved regardless).

If I decide to write the code for "Comment author must have a previously approved comment" myself, will I be missing out on other built-in protection that WordPress offers on comments?

I would like to still get all possible protection from spam that WordPress offers.

If the Settings->Discussion options don't work, does that mean that activating the "Akismet" plugin will not have any effect on eliminating spam either?

Thanks.