Fixing the bends
There are a number of prepainted plastic miniatures available now. The nice thing is that they tend to be relatively cheap. Plus they are already painted for those that do not wish to repaint them. The big draw back is that most are made out of some type of plastic that is quite easy to bend.
A number of fixes have been suggested, like using very warm water to make the figure pliable and bend it back into shape or using a hairdryer, etc. Personally I haven’t found any way that really is permanent. The straighten figures tend to eventually bend again or the part is just too thin to stay rigid.
So what I do now is kind of like external pining or bracing of parts. I use medium gauge guitar string (on the ribbed/wound strings) as it is very rigid for such a thin wire. I am sure you can probably get thin gauge brass rod from your local hobby store to use as well. You take the wire and find an area on the model that the wire can blend into plus a place to anchor it if possible. Then just drill out a tiny hole to anchor the wire if possible, then the wire to the desired length and super glue it in place.
For Destroyer Droid below I ran the wire on the shoulder supports and anchored that into the box shape on the chest. For the Clone Trooper I ran the wire under the gun and anchored it into his hand. It is a pretty simple procedure. You can even go as far as drilling a hole into the legs of other areas to straighten a figure out.