Should I be worried?? (importing not capturing .avi files)

I shot a movie on miniDV years ago and am finally trying to get it finished up. A friend uploaded all the tapes for me onto a hard drive as .avi files. I have been editing (using Final Cut Express) by importing from these files directly off the hard drive using in and out points for the timeline, NOT actually "capturing" any footage (so I don't have any clips in bins, only on the timeline).

Recently a friend who knows more than I, but not enough to answer this question, expressed concern about how these sequences would export. She thinks they might be interlaced because they're "not native"(??). I am a film/celluloid fogie -- I learned to edit on a Steenbeck in the early 90's -- I don't know _anything_ about codecs (even what one is) or compressing, etc., or too much about any of the actual "digital" side of things... Oh, how I miss my splicer!

This is a feature-length project (28 hrs of footage) and I have spent weeks on it -- I am now about two-thirds done. I just burned a test .mov file (using iDVD, if that matters) that I created by exporting a sequence using the Export > Quicktime Movie > Self-contained" function. I played it on my DVD player and older TV, and aside from the fact that it came out squeezed (not 16x9), it seemed to play all right - there are no glaring quality issues - but the TV is so old, it's hard to tell how it would look, projected on a large screen or played on an HDTV. Maybe it's a little blurry?

I want the best possible quality for the final product -- am I going to have to GO BACK and CAPTURE ALL THESE HUNDREDS of clips now to ensure that? After my friend expressed her concern, I am afraid to proceed! I really don't want to spend another 100 work hours with the .avi files only to find out I have to re-do them. On the other hand, I like the flexibility that importing gives me, so if I could prove to myself that everything is fine, I'd sure be happy.....

Thoughts??
Thanks!!