Can I preview the call before it goes live?

Set the status of your call to "Show to entrants and jury" but keep it hidden from the call list by turning off the option "Publish to call list" directly above the status dropdown.

Then logout, go to the signup page and register as an entrant with a dummy email and go through the entry process to make sure it's working the way you want. You can also stay logged in as admin, open your EntryThingy page in a different browser (eg Firefox if you're logged in as admin in Chrome) and register as an entrant there.