That's a trial and error process, you rotate the bones around and see if it deforms correctly, there's not set values for this. What i did is weight the head 100% to the cranium bone and do the same for the face and then started distributing weights to face bones. Doing this will ensure you locked the border vertices were the face/head are detached from each other.
It's still the same deal as the face, once you have done them however, you can leave them with the skeleton and re-use when needed, no need to redo the weights everytime, just like i did with the tags.
(If you temporarily want to get over that hurdle, simply weight all the verts to the hand bone.)
Tip: In max pressing E should center your view to the elements you have currently selected, this is especially useful in a tight spot like the hands.
-All the meshes you have merged together should have kept their UV's so the only thing you'll need to do is go back to original model folders, open the .skn files in notepad, select the body parts that you used, paste them in a new file and change the path like this:
throw all the textures in "models/players/yourplayermodelname"