Addressing the title of this thread: no. Not by a long shot. So long as there is a need for Android applications, there will likely be Java.
Um... it is slower than other languages in certain cases, and much faster than other languages than others. I don't think Java is inherently slower than "other languages"... just that other languages can perform particular tasks faster and, conversely, Java can perform certain tasks quicker than other languages.
Nope. I quite like Java... it has a nice syntax.
Nope. It's still the second most popular language on Github, followed by Python.