I have an exo terra, basicly the same only cost like 100 more lol.
the only ive done is new gmade shocks. Idk if it has the same nose dive problem the exo has/had, I put 40wt oil in the front and 50wt in the back. That fixed it.
Go on youtube and search it and see if anyone has videos of theirs.

As for lipos, they need to be maintained. The mirage come with a 3s lipo. The esc on that should be set to cut off b4 it over drains it. Get a good charger like the thunder ac680 its like 55$ and does everything.

If u need more info just ask