Firstly, there's a patch for the user import/export plugin that should solve some problems:http://pkp.sfu.ca/cvs/cvsweb.cgi/ojs2/p ... 14;r2=1.15
1. If a user has several interests, do they each require a separate <interests> tag? Is the locale required?
Currently, you can specify one <interests> tag for each locale you want to enter information in.
2. What about line returns in mailing_address? Shall I just replace them with commas?
Line returns are fine as it's a multi-line field.
3. Can passwords be added "in the clear"?
If passwords are entered with the attribute encrypted="plaintext", they'll be encrypted by the system when they're imported. Otherwise, specify encrypted="md5" or encrypted="sha1", depending on whatever is currently used in your config.inc.php, and the hash will be entered directly. It's not possible to extract passwords in plaintext, as they are stored hashed for security.
4. The import dialog seems to be specific to the journal: what happens if you want a user to be on more than one journal?
You'll have to use the Sync Enrollment feature from the other journal's interface.