Do files lose quality when being re-rendering mulitple times, if its within the same timeline? I have a project that I am constanlty making changes to. I then print to dvd to inpect the changes. Each time I do this, the file is re-rendered. Since I am making the changes directly to the time line, will there eventually be a loss in quality? Or is the answer no because I am not re-capturing and importing new video that has already be outputted once?

Re-rendering doesn't make any changes to your input file. The only time that you will lose video quality is if you render and then use the rendered file as a new input file.

You don't have to lose quality when rendering to a file that will be used as source footage for editing later. You can use a lossless codec (either uncompressed or using lossless compression), or you can use a codec that utilizes what is generally regarded as "visually lossless compression" (like Cineform's codec).