1. Midnight UK time is 8 pm WDC time. That's if I'm doing the time zone conversion correctly, which I've been known to mess up, so hopefully someone will correct me if I'm wrong. (WDC time is UTC-4 during Daylight Savings time (currently active) and UTC-5 during Eastern Standard Time. I think. And as far as I know, the entire UK is UTC0, because Greenwich and historical reasons and whatnot.) Now, I'm not sure what you mean by "lockout," but you don't have to have something done by midnight - just don't go more than 72 hours between logging assignments to stay eligible for the primary reward.

2. Someone else will have to chime in on this.

3. Best thing to do is ask here in this forum. If you'd rather email someone privately, probably your best bet is to post to that effect here, and hopefully someone will get back to you soon, depending on their own schedule.

4. So, what you need to do if you're posting the work on WDC and don't want the general site to see it: when you create or edit an item, there's a dropdown option to limit access. It'll have selections like "Make Public," "Registered Users + only," "Registered Authors + only," etc. Also on the dropdown are options to make the item visible only to a group. Look for the Prep group option. (Note: you don't have to post anything here on WDC, except for contest round entries, and then only if you want to participate in the contest.)

5. You're definitely not on your own. This forum is for asking questions and getting help.