Quote: "When I offset them they do not come apart from the model(they stretch)"
This may happen if some vertices of the models limb belong to another part of the model. For example if you have a human body model, some vertices of the arm like the shoulder would still belong to the torso. So if you then move the arm limb, the shoulder vertices will still stick to the torso, thus resulting in a stretch effect of the arm (like the biceps and such).
Quote: "I can't show/hide them indiviually"
I once had this issue too. I guess it has to do with the bone/limb setup of the model. I think it only works if the limb you try to hide is a closed mesh on its own (like no shared faces, etc.). So far I have no solution except changing the limbs setup in a modelling tool...
Quote: "is there any way I can setup the limbs for these models myself in a modelling program"
For such task I use a combination of FragMotion (.dbo import/export, animating) and MilkShape (creating bones, preparing geometry for animation). I think both tools are awesome and affordable. If you then throw Wings 3D in the mix, the modelling world is yours
But remember, it all depends on practice. Took me quite a long time to get my first good looking complete character (geometry, skeleton, animation, skin) working.
Now the plot thickens, the fps decreases, and the awesomeness goes through the roof.