Ok, if you are going to move stuff then I think soft selection (a tab within PSR tools) is most useful to you, in conjunction with a few of our selection tools to make sure we are only moving certain things...
For example, in poly mode, you could start with U,L (loop select) to grab a loop high up on the arm, then do U,F (fill selection) to grab every poly under that to the end of the fingers in one easy click... and then you can put the modelling axis in the most helpful place for the operation at hand (axis mode or sliders under tool attributes), turn on soft selection in any component mode, set a suitable radius and start massaging things in the right direction, using perhaps the standard transform tools in conjunction with Brush / Smear tools to make things go where you want them. Here's an example of how you might do that...
So here I have a low poly model of a larger gentleman with his arms in wrong place. I have done the above and selected all the polys in right arm, engaged soft selection (surface mode so we don't grab his body too by mistake) and moved and rotated the axis so it lines up with his body in a way that will be most helpful to me then rotating it from that point, straighter.
So using mainly rotate and move tools I can now get his arm vaguely where I want it, like so...
and I can keep adjusting until it is mostly right, and then turn attention to the now mangled loops in the transition area.
For these we can move into Edge mode, get the Move tool, and double click to get individual rings of edges that we can then move about to even out the transition and hopefully avoid any intersection.
Whilst we are in the modelling tools though, a number of other things there are likely to be very helpful; Iron (applied to the polys around the transition point) and Brush (smooth / relax modes) both do superb jobs of smoothing and untangling any bunched up or intersecting polys. That way I can get his pose exactly right, more like this one...
The important thing whilst doing all this is not to actually add or delete any points / edges or polys to this mesh, which will break your UVs if you do - the mesh's point count and order must remain the same in order to preserve that, but apart from that, you can do pretty much anything you like to your base mesh before you rig it !
Hope that helps
CBR