Hi! I've searched for this answer in the forum but I couldn't find much about invite codes.

Invite codes:
Is there an option to allow registrations with invite codes only?
I was thinking about using zenphoto for a preschool, only parents are allowed to view photos so I need a system where only people who received a code from us could sign-up. Can zenphoto do that?

Downloads and stats:
We're going to upload zip files only. Is there an option to see who downloaded what?

Password:
How secure is zenphoto? Once an album is password protected only logged-in users can see it?

View rights:
Can I choose who sees what? For example restrict 'user1' access to album A and B but allow him to see album C.

File size limit:
Is there a file-size limit for zip/rar files?

[i]Invites[/i]
No, nothing for that exists

[i]downloads and stats[/i]
If you modify the the theme used you can use the downloadlist plugin to get a download count. There is no way currently to see who downloaded what at the moment.

[i]password/view right[/i]
Please see: http://www.zenphoto.org/news/an-overview-of-zenphoto-users

[i]file size limit[/i]
Your server sets the limits. Uploading .rar files to the gallery to be extracted to albums is not supported btw.

Invite codes:

You can create the userID and have zenphoto e-mail it to your user via the [i]email-newuser[/i] plugin. Not quite the same since the ID is created even if the user does not want to sign up.

You could deal with that by using the [i]user-expiry[/i] plugin to purge userIDs of people not visiting the site.

Of course setting up user accounts beforehand would be the simplest way especially if the user base is known (as it seems to be on a preschool I guess).

especially if the user base is known

Pretty much has to be know to send invite codes.