Well, it varies a lot. The fat_bdsm list is fairly low traffic, with only a few messages a week. The fat_sex list goes from slow periods of only a few messages a day, to a few dozen. The new announcements list will only be posted to once a week, at most, and usually a lot less. I don't want to deluge you all with commercial announcements!
Sure...send me a note at firstname.lastname@example.org and let me know what the problem is. Be aware that it may take me a while to take care of the problem. Also, sometimes it takes awhile for the list to get to a message, so sometimes you'll receive some mail AFTER you unsubscribed, or it may take while before you receive mail after subscribing.
Not really...definitely no personal ads or (gah) weight loss snake oil. There are some times when I'll permit something to be posted that is of relevance to the list in question, but it must ALWAYS go by me first -- no exceptions.