300 dpi is no problem, but that doesn't tell me how big you want it, can you give me a figure in pixels or inches? As for the background, if you are going to remove it totally then I can render the image as a TIFF file with an alpha channel and save you the work.
I will see if I get time at the weekend, would you want fully coloured valks, or greyscale so people can make their own custom colour schemes? If I don't have time you could perhaps talk to scott8539 as he already has the models, or indeed you may have the models yourself by then and not need me anyway.
I'm sorry mate, I never thought about that, I first started using Cinema 4D back in my Amiga days and when I had to move to the PC I continued to use IFFs out of habit. What you need is Irfanview, its free from http://www.irfanview.com/
If you deal with graphics files it is a very useful tool, its one of the few programs I feel I absolutley have to have on every PC I own.
The batch conversion function in the File menu will do what you want in no time flat. Just browse to the directory with the tex files, change the "Files of type:" setting to IFF/ILBM, highlight the files and click the "Add" button, make sure Jpeg is selected as the output option and click "Start."