Upload & Sell: Off
I've spent and sold about 10K on the FM b/s sell board, including returning one body with blown pixels. All no problems. Do you homework (ratings, communication) and trust your gut. Others, of course, have had less enjoyable experiences.
As for focal lengths... I like the SI ethic I saw somewhere once... longer than 600 and wider than 24, but I'm strange and often shoot way too tight (and sadly have a 500, not 600). Since you're going to be shooting indoors predominantly have you though of a 1D Mark 3 for a second body? Great camera when it works. The real issue with the affected bodies was that they couldn't focus worth a damn in sunlight. They were still pretty good in the dark, i.e., indoors.