Pong bug 1 and the flag return on new round bugs have been fixed (same bug - things were still moving after being reset). Pong bug 2 isn't really a bug. It's just imprecision in the Quake2 engine. The ball is actually bouncing up and down slightly, but since the server only updates at 10hz, and the units are kind of rough, that's the result. It's a lot better than what I used to have where the ball wouldn't stop bouncing or would float around or get stuck.
Bug 3 looks a bit weird, but I'm not sure it's entirely incorrect. I think it may just be too bouncy. I can tone down the bounciness of it a little bit. You can actually tweak the "bouncescale" cvar. Bug 4, I think you just got lucky. The ball bounding box is really a cube, so it's possible to get it stuck on things like that. (On a side note, those textures are way too bright).
I'm looking into the build check failed kick now.
Oh, and I somehow completely failed to include the latest game dll in the build 31 release. Guess I'll try to make another release soon so win32 servers can have the interpolated hitboxes.