Training? I do not believe so, but I believe the sav has the ability to learn and likes to keep a tidy cage. they will usually go in the same corner or spot. I thought mine was 'trainedto only go poo outside but she was just trying to tell me she needed a bigger cage, cause after I built her one she started pooing in the cage again.
It is better to have a custom built cage that can handle the heat, humidity and contain the lizard without it getting out, which is a challenge sometimes. Rooms are built to do the exact opposite of what savannah cages calls for, as SHvar will tell you. As far as aggression goes, depends on the lizard. I would try to find one captive bred, for sure. Get it small, as a baby and do a lot of handling then, if it is willing, if not leave it alone and handle on it's terms. I have one now that i raised from a baby who is like a 4 foot long puppy dog, and another one that i bought as a yearling and he is testy, so it just depends. The puppy dog one has not always been that way; it took a lot of work. search the forums because I have posted about every question imaginable and have been posting since i got my first sav almost three years ago, so i have left a pretty good trail of info and the people (some people) on here return very good information and really know what they are talking about.
Good Luck!