After recently discovering what PR and SEO even are (yes I feel extremely stupid for not researching this long ago) , I've recently started manually submitting my site to the following free directories in an attempt to up our back links and PR.
http://www.web-directories.ws/General/Free/page-1.html

EDIT: Side note, is it worth it to submit to directories with no page rank? or should we stick to the PR 1 + sites?

Between myself and a few members of the staff willing to help out with his boring task , we've covered around 400 thus far in about a weeks time. I noticed after the recent Alexa update that our 1 week average had dropped nearly 100k ( www.e-rev.tv) , is this due to the directories reviewing our site? Will this spike back up when we finish the submissions?

Also , I've done as much research as I can on google PR, and I can't find a solid answer on when google PR updates. Does anyone know the time frame they use and when the last update took place?

Appreciate the help in advance.

-Erick