Hi,
I read the thread and had a few point-outs on this matter, I was in the same pot a while back when I started with timelapse...
First of, the amazon link to the TC wont work, that is the model with the 2.5mm stereo plug, you need the N3 connector for the 5d3. Get something like this tc-80n3
.
Second, if you have a large enough CF (SD) card, always shoot raw, especially in light changing and challenging conditions.
Third, mentioned above, always set everything MANUAL, you can measure the exposure in P mode and then roughly transfer the settings to M mode.
Fourth, Use lightroom to edit and sync the edited image with other images in the sequence. after you sync, export all to a folder to JPG and desired size... open QuickTime 7 pro (version 8 does not work), click FILE, chose OPEN SEQUENCE... chose the speed (fps) and voila, all done... if happy, save/export file to mp4/avi...
Good luck and have fun.