When you say "nothing happens," what do you mean? Do you get a blank
screen after saving the item? Do you stay on the items/edit form, but
the checkboxes dont' stay checked? Or do the checkboxes stay checked
but that item doesn't appear on your public theme as public or
featured? Or something else? Turning on Display Errors will probably
help us debug this issue too, so do that before trying to save the
item again. If you have a public URL for your site, could you could
share with us? That might help us answer some of your questions, too.
As for the admin logging in, it sounds to me like it might be a issue
with .htaccess or url rewriting. There are several possiblities:
1) You don't have mod_rewrite on your server. Check with your system
admin or host to confirm this.
2) You do have mod_rewrite, but don't have an .htaccess file in your
'admin' directory. If this is the case, be sure to upload
the .htaccess file that comes with the zip of Omeka.
3) You do have mod_rewrite, and do have an .htaccess file in your
'admin' directory. If this is the case, I suspect you have
another .htaccess file somewhere else on your server that is
overriding the rules in the admin one. To, add RewriteBase /admin/ to
your admin's .htaccess file, right after the "RewriteEngine on" line.
Let us know if this helps!
Jeremy B.