Well these are lots of questions at once! I'll try to answer actually some of them...
First thing: What is a bandolier? Is it really a belt for patrons? That is the translation my dictionnary told me, but I wonder what you'd need them for with LotR miniatures!?
Head swaps: I don't think there is much to say about it. Look for the miniatures you want to change the heads of, check at first whether the size fits and then cut the head(s) of. You can glue the new head on the miniature or drill wholes in each the bodie and the head and use a piece of wire as a peg (right word?). Then you take a piece of putty and attach it to the gap. Depending on the miniature you then have to sculpt hair (simply carve lines with a needle in it), fur (shorter lines overlapping each other) and so on, for these things it is the easiest to look at the structure and try to redo it.
repositioning limbs: Again not too much to say, as Goldman25 said you have to bear the anatomy in mind. Anything else is similar to head swaps.
Sculpting cloaks: Just take a look here, it is a (German) tutorial on how to sculpt cloaks by me. It is simply making a base coat with putty in the shape that you let dry. Then you role out some putty and attach the roles on the cloak to create folds. The last step is blending these folds together, very usefull tools for that are clay sharpers. I hope the pictures explain the most of it.
Belts: Just role some putty out and flat it. Then you can cut out a stripe of putty in the right size and attach it to the miniature.
Or you attach a thin role of putty that you flat on the miniature itself.
For anything else I can just tell you to look at some sculpts and imagin how they were sculpted. There are thousands of things you could explain, but often it is more usefull just to try out on your own.
I hope this helps a little, if not you're very welcome to ask me something (but I don't look in this topic too often, a PM could be useful
). And please excuse the grammar and spelling mistakes, I am to lazy to read this whole post again... 
Cheers,
Bennet
