Ok for your first question, joints are what rigging's about primarily. However, before you shoot the answer down, any character that you want to move has to have the joints implemented into the skin of the character, otherwise it can't be animated easily. You first go in and place the joints in the areas of the character that are going to deform properly, ie.. any joint in a real person or animal, that would move. Tho you need to go crazy with them, like say the spine; depending on the character and even how realistcally you want the character to move, you can have anywhere from 3 to the actual amount of vertebrae the character would have. Tho, I usually go with about 8 or 9.
Now once you have the joints there you have to go in make sure that each one is properly oriented. Sometimes, the best way to check is select each joint in a chain and use the rotate tool to see how each rotates. Normally the default rotation will not be correct. The long way to fix this is to select the joint go into component mode and select the ? button will allow you see the rotation axis of that joint, looks similar to the axis at the bottom left of your camera view panel. I've found that having the X axis of the joint pointing at the next bone in the chain works the best. To change the axis just select it and use the rotation tool like you would for anything else. Once you have the x axis (or which ever axis you choose) pointing to the next joint, rotate the around that axis till you have the other axes pointing the directions you want. Then go and adjust all the joints the same way, keeping the axis oriented relatively similar.
Once all the joints are ready, you can technically animate the skeleton as is, but that doesn't help quicken the pace for the animator. Usually it's good to make control curves to move the skeleton around. Just draw out curves using the CV Curve Tool, place it at the proper location for say the hand, or whichever body part you are making control for. Make sure that the control curve has all it's values frozen, otherwise it's not really going to be that helpful for the animator when the start position is not at 0. Helpful to actually group the control to itself and then move, that way the curve's transformation values are at 0. Then it comes down to how you want to move that section of the character. You can either just use constraints to have the control move the proper joints, or even parent an IK handle to the control, if that's how it moves.
Once you have your skeleton and controls set up, you have to bind the the model to the skeleton. Either Smooth or Rigid Bind, primarily characters will use smooth bind. Select either the main joint of the skeleton or better to go in and select only the joints that will really have the main influence on the character's movements and deformation. Then select the model and select the Smooth Bind tool under Skin> Bind Skin. Now you have it bound, and you can move your character. But hold on, there are very very slim chances that a default bind will bind correctly. Now you have to go in and adjust the weights of joints on the skin. This means that you adjust the area of the skin that the joint affects. You can do it more manually by going into the Component Editor and type in the numbers for each vert or cv on the model. But there's a little bit easier way. You can paint the weights on to the character for each joint. The tool is located Skin>Edit Smooth Skin> Paint Weights Tool, it's usually best to have the option box open while doing the painting that way you can select the joint you want to work with easier. One important note, never use the Replace brush, for some reason it barely gives you the results you want. It's better to just add a negative value if you want to get rid of an area the joint is affecting, and really only if you have to. Primarily you should just switch between the joints in that area of the model and adjust their weights accorrdingly. NOTE: Weighting a character is primarily where most of your time is taken up when setting up a character. So don't think that you'll have it done in no time. Might be good to do an area of the character and then move the control for that section around and see how the area deforms. Or if you want put a simple animation together and just hit play when you want to check how the weighting is going.
Hope some of this imformation helps, it's just somewhat of an overview of the process. I would really suggest finding some tutorials and/or dvds that can help you delve deeper into it if you are really interested, that is if I didn't just scare you away with all that goes into setting a character .
John 'Zimm' Zimmermann
“Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world." - A. Einstein