Hi Sandi

Firstly,please assign your domain to your license to obtain for support. You can do so by accessing your license area at http://stackideas.com/dashboard

it looks like some standard Joomla user fields can be edited there. Can custom Joomla user fields be edited there?

-> I'm not sure which custom Joomla user field that you referring this to.
I am really sorry but unfortunately we hardly accommodate your request currently as it is beyond our support scope's policy as outlined in http://stackideas.com/support

Perhaps you can customize the file below:
JoomlaFolder/components/com_easyblog/views/dashboard/view.html.php function profile

and display file:
JoomlaFolder/components/com_easyblog/themes/wireframe/dashboard/account/default.php