I've run at least part of ALL of the 5e adventures. I've run Out of the Abyss TWICE. (Actually, come to think of it, I haven't run Rise of Tiamat. So if any of you are running them and nee some advice, I'm here for you.
As far as the beginning of Horde goes, just remember the bad guys aren't there to kill PCs (in fact, there's so many of them, they're more likely to assume that the PCs are on their side). The best way to avoid a TPK is to (after you've made sure that the Players recognise that they are totally outnumbered) is to have the chaos of what's going on work in the PC's favour.
As far as the Adventure vs the Adventurer's League goes, I'm happy to run anything. It's just that I told you to make characters recruited to work on the curse, because I read about that in the AL adventure background. You made those characters, and have been asking questions, but the AL material I have has NO ANSWERS. Because THAT story is in the 'real' adventure. The AL stuff that I have is all mini-missions that don't go anywhere, really.
But I'll get the real adventure tomorrow. So we could switch. Or do BOTH, or whatever. I'm easy, so I thought I'd see what you guys think.