Our most immediate goal is to be able to run traditional web apps written in PHP, Ruby, Python mostly unchanged but with the additional layer of isolation and sandboxing. We see this (once fully matured) as a great way to improve security without changing how web developers work
Not with that level of granularity. Wasm is able to run in severely constrained environments (ie microcontrollers) and non-posix OS that may not be able to support containers
Sure. Everything in computing pretty much builds on top of everything else. Wasm is no different and incorporates a lot of the learnings from previous technologies like Java and .NET