I still think it's a bad idea. Why would you import the entire source code to another language? It would take a lot of your time up and the end result would not be the same. IVAN gameplay is very precariously balanced and even the smallest change would upset that balance. I'm also pretty sure the way they handle graphics in IVAN would be impossible to replicate in Java.
It would be much easier just to learn the basics of C++. C++ is an extremely easy language to learn. Much easier than Java. The only thing you need to learn pretty much is networking, which is fairly simple... Trust me, keep it in C++. This is a great idea but trying to import it to Java would just kill the project
Yes welcome aboard. I'm of the strong opinion that it would be best to keep it in C++. Much less work, C++ is a much more flexible language in my opinion, and definitely much faster than Java.
But multiplayer would definitely be great. As for the levels I couldn't tell you how they are generated, but they are not entirely random.