Did the Portal 2 saves get deleted

I've had this happen to me. I would guess your internet connection gave out or you were not logged in to steam. IF you're lucky the achievements were saved locally and will upload once you login to steam. But chances are you just need to get them again.

'Portal Standing' and 'Peek-a-Portal' don't work the same as they did before, but the same effects can still be achieved.

Here's something cool done in P2 with Peek-a-Portal:

Here, while peeking through the orange portal to the blue side he is able to place another blue portal from the blue side while moving back to the orange side. Just like Peek-a-Portal from Portal 1.

As for Portal Standing, you can't use the ledge of a portal as a place to stand even while switching portal locations, but by carefully jumping through a portal and back, placing a new portal in between. You can jump from your blue portal, to orange, place a blue, and come back out the new blue side, even if there's no way to touch ground on the orange side. An example can be seen in at 0:09 of this level 5 speed-run:

A bit later in that same video, there's a third glitch you haven't mentioned yet, guy uses something he describes as "Portal change cube grab". It takes him 3 tries, but basically, he switches the location of the blue portal just as the cube is falling through the blue portal, and he's able to grab the cube as it's leaving the orange portal but before it's launched away. Maybe this isn't a glitch, because the mechanics make perfect sense, you just have to be really fast. It probably wasn't an intended solution though.