First rights given away?

This is a pretty generally used rule of thumb. That is why the Share Your Work area here has a password.

Posting on TheNextBigWriter or similar forums like it isn't the same as publishing the work, nor does it "count" as a publication credit. The only instances where you might need be concerned is if it's an online journal--then it is considered the same thing as being published in a paper journal, and you will have to obtain permission to be able to publish the work elsewhere.

I couldn't open the link you gave, Cattywampus, but I found the article here: http://www.sfwa.org/beware/epublishers.html

The last paragraph in the article states:

(Password-protected display or critique sites, such as those run by various writers' groups, are usually an exception, since the work there isn't visible to the general public.)

I would think it also applies to critique groups that are not private or password-protected. But you run the risk of anyone coming along and stealing what you've posted, publishing it before you do, and claiming you plagiarized.

On some writing sites, group managers claim they hold copyright to what a member has posted. I know that's BS and you know that's BS, but there are quite a few people running scared.