Answer 1

https://www.sololearn.com/discuss/555754/?ref=app
https://www.sololearn.com/discuss/272458/?ref=app

Answer 2

it really depends on what you are trying to achieve. java will work just fine for most algorithms based on neural networks and for it being not native code its actually relatively fast in the learning process. but you can clearly notice a difference after some learning time to the same algorithm in c++. you will notice that c++ is quite a bit faster even without much optimisation or correct threading. But in my view java will work just fine for most cases :)

Answer 3

i'm not so sure, but you should try something with dynamic memory allocation like c++. also c++ is super fast, something youll need to process all the input you'll need.