I may need to be using GIMP for this but I thought I'd ask anyways.

What I'm doing is rendering a 3D model as a raster format from my CAD application. What I'm trying to achieve is to import this into Inkscape (which works fine) and put our company logo and some other graphical needs (text, sometimes a watermark, etc) over the image. The problem is when I save/export, the original file's resolution is badly mangled, seriously degrading the quality of the original image. Is there a way to retain this high level of resolution?

Thanks in advance!!

i don't heave a ready reference url to the posts, so you'll need to search the forum...there's many posts about png export. the main thrust of it is to snap to a pixel grid, which prevents the raster export doing sub-pixel approximations.
by the way for the needs stated, you could set up some commands using ImageMagick, which can repeatably put a watermark/logo resize etc. without loading a graphical editor for each file.

Extensions > Modify Path > PixelSnap will automatically align to a pixel grid. This might solve the problem, I'm not sure. But easy to try

Wow, not bad. That actually works pretty darn good. I still may need some more tweaking but that definitely gets me closer to my overall goal. Thanks for the tips guys!!

Just one more quick thought, and you probably already know this. But just in case, avoid scaling the raster format.