Question about encoding / rendering multiple times
The question's not entirely clear, but, yes, each new generation of the rendered file will lose some quality if you use the previous generation as the source, but not if you use the initial H264.

To elaborate, let's call your raw capture as Generation 1 or Gen1. Then your H.264 transcode is Gen2. Now, after editing with Gen2, your export is Gen3. Now, if you open Gen3 and edit that, then the new export will be Gen4 and will have lost some quality (certainly mathematically, maybe not subjectively). But if you reopen Gen2 and edit it in a different way and export it (with the same settings) then the new file will also be Gen3 quality.