Do I have to give it my marketplace password?
Yes, and it is fair to want to know where that goes. You enter it once. It is stored encrypted against your account and masked everywhere it is shown back, and it is used to sign in the same way you would, from the computer the app runs on. Change it or clear it in settings whenever you like. Clearing it deletes it rather than hiding it.
How soon will anything actually be listed?
Once your lot is in and your description is set, the drafts are there to read. The first listings go out the day you approve them, and the rest follow rather than all going at once.
Will it wipe out the listings I already have?
No. Anything already out there is matched to the vehicle it belongs to and left where it is, so you keep the age and the history on those listings. New ones only get created for units that do not have one yet.
Do I have to approve every single car?
The first time through, yes, and that is deliberate. Nothing goes public that you have not read. After the first batch it only comes back to you about new arrivals, which is a handful at a time rather than your whole lot.
What if my dealership isn't in your system yet?
Send it over on the find your dealership page. No account and no card to do that. Most go straight in; the rest somebody sets up by hand, and you get told when your lot is ready.
What happens if that computer gets shut off?
Nothing goes out while it is off, and nothing is lost either. The queue is still there when the machine comes back and it picks up where it stopped. This is the reason to install it on a computer that stays put rather than a laptop that goes home at night.