[Steven Zahm]

@ Peter

RE: it works for a few seconds and then reverts to the old form with title, organization and department displayed.

Hmmm, yeah, I did not think of that. What you are seeing is correct. When the form is loaded and the user does not have a choice, the proper fields will be shown. Not sure this will work either but try this instead:

#cn-form #cn-metabox-section-title,
#cn-form #cn-metabox-section-organization,
#cn-form #cn-metabox-section-department {
    display: none !important;
}

RE: can I lock the Category field to only accept “Member”

Set the default category to the “Member” category. The on the Forms settings tab, uncheck the “Categories” option if the Fieldset section. The entry submissions should default to “Members” without give the user the option to select categories.

Hope that helps!