is there any way setup a catch all redirect for all sub domain so *.mydomain.com will all be redirected to www.mydomain.com ?

is it possible to set it up for add-on domains?

Yes it is possible.
You can set up redirection from your control panel or open a trouble ticket and we'll set up a catch all redirection for you.

Best regards,
Slavik Koshelev

Is it possible to have a redirection from.. let's say, any attempted subdomain that is non existant?

Like:
exists.elpea.net would go fine

but, doesnotexist.elpea.net would redirect to elpea.net

Yes you can set up redirection.
In this case you should edit .htaccess using Rewrite Rules.
You will find more information how to do this by the following link:
http://apache.org

*sigh*

Alright, I'll dig.

Elpea:

i use networksolutions.com for my domain registration, and they include dns tools in the package i have with them that allows me to do all my own editing to anything dns related to my domains such as "a records", "mx records", "cnames", etc..

i have set up as what are referred to as "A Records" the following three settings:

www.mydomain.com = xxx.xxx.xxx.xxx
@.mydomain.com = xxx.xxx.xxx.xxx
*.mydomain.com = xxx.xxx.xxx.xxx

i use the same ip for all three entrys, and this points any and all references to the server i use for my domain.

in addition, i do have a couple of sub domains set up, and when i add in the "a record" that points to a different ip, they do properly get directed to the correct server, as i have these subdomains hosted on a different server than the main account.

if you have the ability to edit your dns settings, this may be the easiest way for you to do what you want to with your site.

hope this helps, if not, sorry to have wasted your time..