Try adding this to your htaccess file:
AddHandler python-program py
AddType application/python py
You may need to refresh on that file you were testing after you add that.
I'm thinking that some of your 500 errors were just a coincidence of the problems we have been having over the last few days and nothing to do with your site. If you keep having the same problems let us know.
You can't add the www as the domain name because www is a subdomain of your site and it gets added through the cpanel. You'll still be able to go to your site through www after you create the domain. Your addon domain should show up in the list in a few days if you corrctly added it.
Sorry you had a bad experience. Normally it's not like this. Crond went down for a few days without us realizing it and we got a backlog of new accounts. It should be straightened out soon. Let us know if you find a free host better than us.
We have a significant number of new accounts still in queue and yours is one of them. Please give it another 48 hours and post back if it still doesn't show. Sorry!
I'm not seeing this domain in our database:
onlyjeff.heliohost.org
As soon as signups are backup you should be able to register with that same domain name and username.