And the pair is determined by Zenphoto from the files permissions by "ANDing" 0111 to it. Thus $conf['CHMOD'] = 0644; yields 0755 for folders.

Reinstalling now (waiting for FTP of all the files to finish). Every time I install ZP, I get: Zenphoto suggests you make the sensitive files in the zp-data folder accessable by owner only (permissions = 0600). The file permissions for setup.log are 0644 which may allow unauthorized access. What should I do about this? I usually just ignore it...

Probably for your server you should ignore this, but understand that these files might be vulnerable.

But that you get this error at all would indicate your site has severely restricted what applications can do with regard to setting file permissions. (Either that or you are not running current Zenphoto software. I do hope that you checked and are not making that mistake.)

Sometimes hosters get a bit too aggressive with their security and cripple legitimate applications. All totally unnecessary and a bit naive of them.

Is there anything in the files I would care about? The public can only read them, right? And they aren't advertised.

Well, for instance, your MySQL credentials are in the configuration file. You probably don't want the public to read that. They are not advertised, but any hacker worth his salt will have read the Zenphoto code and know how to find them.

Okay. So should I set the permissions of the files to 600 and folders to ...?

Also: HostGator said that the FTP account and the admin account were the same, so "owner" will always be me.

I cannot make recommendations for your host. If he is correct then the settings from setup would work. Since apparently they do not something is amiss.

Site is up and running, added that code to the config file. I uploaded a test image and it worked! Now what should I set the permissions for the zp-data dirs to? Files are 600 now.