Well, basically you don't need any custom libraries for Java or any other language unless you're about to use object-oriented bindings to Tor Control Protocol(you can use it as a plaintext telnet for a simple commands like SIGNAL NWEWNYM to change the circuits - it will be handy for a data gathering you've mentioned). All you really need to utilize Socks5s ...
Well, the ones you've mentioned - are very long-term ones and yes, they are using Tor. I2P has got some good amount of non-public outproxies, and that is how it has to be:
Same as Tor's exit nodes, outproxies are diversifying the ways/IP zones of the exiting traffic
Instead of Tor, private outproxy can be easily specified on-flight and used by the I2P ...
Sure you can! Tor.exe is a standalone daemon that can perfectly fit even a case when it is executed as as system service! Just put it all on the right place - and enjoy! If you'll describe your particular case - I think I'll be able to help you better - so just expand your question!
It's a windows 10 bug - it binds some of system services to it - and I bet it's done on purpose! Just choose another port - I used 9999 or 19999 - and it worked well. Microsoft has it's affiliations with a privacy-invading state structures, you know - so it was quite an unpleasant surprise for me too like a year+ ago. Just change the port - and that's it.
yes it's safe, because the directory services' keys are hardcoded into the Tor source code itself so no data breach will be possible. The proxy is just a way to connect to the dir's and peers. But if you're behind the proxy - then you will be unable to accept ORPort incoming connections and it's not good for the speed and decentralization of the network.