You can choose whatever suffix you want: .htm, .html, .asp, .jsp, .blah you name it.

What do you mean a white page? Make sure you don't have a directory called "downloads" on your server.

Yes it does, but that has to be done manually for each URL.
You can read the documentation for more info or download the free trial and test.

Only the static content will have "first directory" form. For other content you can use manual alias.

Sure, you do it in SEF Advance configuration, Strings Tab, components with SEF extension. Enter: docman=>downloads

It worked fine for me on latest CB and latest JB. Try viewing your own posts.
I will have another look for posts of others.

Meaning what?

If your static content has a title "ai24567" and you have ".htm" suffix then you certainly can.

If it contains Google redirect line of code then mod_rewrite is not working because http://esc65.midphase.com/~newellcr/google.html is not redirecting to Google.

Actually, on the second sight, registration links are SEF-ed, just not enabled in SEF Advance.
I will take care of it for the next version, thanks.

Registration component doesn't have any Itemid so only items assigned to ALL pages will show on it.

Must be something with .htaccess
Can you post its content here?

You haven't activated SEF in configurations. I can't see what's wrong.

It's Itemid issue. Please read: http://www.sakic.net/support/faq/sef_advance/#16

OK, I added support for JoomlaBoard Tab pagination. Download the latest version of the extension on the extension page.

Turn OFF debugging in Joomla global configurations.