Jade Bonsai questions
 

I have recently (Yesterday) been given a Jade Bonsai. I am very new to bonsai and am not sure where to begin with this plant. I have read many different posts on jade bonsai, so I don't feel completely in the dark about it, but I do have several questions about taking care of it.

#1- I'm not sure what species of jade the plant/tree is. The leaves are quite small, less than an inch in length and quite sparse. How can I find out which species the plant is?

#2- I'm also not sure how old the plant/tree is. The trunk of the plant is quite thick, over 2 1/2 inches wide and about 8 inches in circumference. Do these measurements indicate how old the plant is?

#3- I feel the plant is in need of some maintenance (i.e. pruning and such). I would like to figure out a certain shape for it. Right now it's upright with three distinctive trunks emanating from the bottom of one main trunk. The tree is 18 inches tall and on the back side is a large "scar" that looks as if a large branch of the tree was "ripped" off long ago. The "scar" is completely healed and kind of gives the tree a distinctive "feel" or "look" to it.
If I can figure out how to post a picture of it, I'll do that, that way it may help with the process of figuring this tree out.

Anyway, any help with this tree would be appreciated.