Doesn't really surprise me. I mean they have said they're working on it, they're just taking their sweet time. People think they forgot about it ^_^
Na, I honestly just thought that they weren't going to release it. As long as it's been I figured they'd just incorporate the episode into Half-Life 3, along with a new engine maybe... Still might be what the plan is though.
It's there alone with some HL1 stuff, so what? Of course they had some pieces of code done before freezing Ep3, remember the original schedule? It means absolutely nothing. *Hint: "Blob spit" - this looks pretty much like Portal 2 liquid mass stuff considered by everyone to be lacking PhysX implementation)
The Episodes are Half-Life 3. And for all we know the episodes will be the last Half-Life product. We do know EP3 is the last of the episodes though, so who knows if they will put out a Half-Life 4 after EP3.