For me, I have both Alice and Lorelai in there..... Emilia and Norah are elsewhere.
As for the rest of the announcement...... I think the biggest thing is this. If a GM has a plot idea that involves EVERYONE (or most everyone, depending), they should mention that in 'announcements' straight up so that EVERYONE is aware of it right off the bat. They don't have to give all the details necessarily since the element of surprise may or may not be key, but they SHOULD say something at the very least. I think this should go for anything be it a big detail or small detail because the GM is a leader here and those involved are going to look to the GM to lead. If that leader fails to lead, then people flounder and have no clue what to do and communication is lost, etc etc etc.
For small scale stuff that involves one or two people, that does NOT require an announcement. For that sort of thing, feel free to discuss things via PMs to start with (ie, pairings and other such things). If little plot-lets form around your characters involving one or two members, definitely discuss it with them to begin with, but then bring it up in OOC so that people have a heads up. It might not directly involve them, but it's nice to be aware of things nonetheless.
Remember, this is a GROUP game. So communication is ALWAYS key. Use your best judgement here. Not everything needs to be announced. But a fair amount does. Especially when it starts impacting the overall RP.