Debating which is the best comment form to attach to a page for feedback.

Are these usually php/mysql database?

I do wish to monitor the posts. I notice it's getting more popular for some sites not to, to keep them closer to real time. But my site has a lag anyway.
Also, the $ sign will be entered by users with the topic(s) covering money and I'm trying to think of the best way to handle this, without manually inserting them, because isn't the dollar sign character part of a mysql injection entry?

Have noticed signup's are not really that popular with comments forms.

Given the above, are most sites triggering emails/csv for upload or posting directly to databases?