Qmail messages stuck in queue because of permission problems

[Mark]

I have a problem with qmail:
Incoming emails are stuck in the queue. It seems like the problem is the
permissions for the queue files - or rather the ownership.
They are owned by root:nofiles. In the maillog if have an entry saying
"deferral: Sorry,_message_has_wrong_owner."

Fixing the ownership and sending an ALRM signal to qmail-send immidiately
delivers the stuck emails:
chown qmailq:qmail /var/qmail/queue/mess/*/*
killall -s ALRM qmail-send

So I added a cronjob that calls a script with these 2 lines every 2 minutes.

Now I have 3 questions:

1. What do I need to do to have the new queue files be created with the
right ownership in the first place, so they get processed properly (I am
suspecting something with the sticky permission flag, but I havent figured
out where and how)

2. I noticed that outgoing emails are still stuck in the queue, but it might
be due to the recipient being a non-existent address. Will those be cleared
out eventually or do I have to do a similar fix?

3. Could there be any problem with my interim cron solution - for example if
I call it too often, etc.?

Thanks,

MARK