so I’m guessing that your source was compressed DV footage …. and you rendered out uncompressed … hence the size difference… if you are not all that knowledgable on compression and codecs do a bit of a google search and you’ll find lots of information….
my suggestion is to render out of AE only the bits you are modifying, then import just those back into your edit program.
With the timecode window you could make a smaller composition that’s just a black solid with the timecode over it and just render that out, then put it on in your edit program …. then you’d also have a timecode window you can keep for future use.
if you must render out the entire program then you’ll need to decide on a codec to use… DV is very lossy but your files will remain small … there are other options like Quicktime Animation, PhotoJPEG, and more…. you just have to balance file size with quality.
hope that helps!