The first problem is easy enough. The way the textures are mapped onto the mesh is designed to save space. What they have done is use the same bit of texture more than once on the shield. It allows you to make that part of hte texture more detailed without using up too much of the limited space available. To cure this, you would need to re-map the shield in Max, so that it lined up with what you had put on the texture tile.

Don't know about finding the Nvidia plugin for Paintshop Pro...I do remember I had to do a bit of trawling on Google to find the one for Photoshop. Best place to look, as I recall, is the Unreal Tournament 2004 websites. They need it for skin painting too. Thats where I found a working link.