These are not for the beginer. Not because they require anything different then any other monitor, because they all require what V.b. mentioned. These monitors just to not have the reserves to withstand lots of mistakes like heavy bodied monitors can WITHSTAND. Keeping monitors is more about mistakes, even with the best of us.
From your question about "do they become docile" I take it you are not very experience with monitors. Please understand, very few people are, so don't feel bad.
If I were to recomend a group of monitors for beginers, it would be Argus and the gouldi complex for medium sized monitors and Ackies, V.acanthurus, from the smaller monitors.
Both of these types are strong, durable, and will teach you about all monitors. Both rarely bite, but of course all monitors can and do bite if given good reason.
Its my personal opinion, if your worried about getting bit. Then its not your time for monitors yet. The reason I say this is, while all reptiles can bite, monitors are inflict lots of pain and damage and with some species, a trip to the hospital. Maybe think of it along the lines of hot snakes. You need experience and training FIRST. Once you get that, then they can be very rewarding to keep and study(notice I did not say pets) Cheers