Check out my
thread on the install process from 2018. Installed on my 2018 30.5MLOK just a couple weeks after taking delivery. The installation too a couple days but was otherwise flawless. The system is still working great 4 1/2 years later.
To answer your question, I did not install a separate 50 amp breaker since it technically would have needed to be run straight to the battery. There was already a 50 amp present that the existing landing gear were connected to so I just tapped off on that.
On your question about the battery box, I was able to keep mine in the same spot, however in 2020 I went lithium and made my own box out of plywood.