Okay I've successfully confused the hell out of myself haha.
This is what I know and understand now.
EZcap transferred the all the videos to my Mac as .MOV (and I had edited some of the videos in an older version of iMovie, again exporting as .MOV)
Toast had the TV Standard set as PAL, and everything I have appears to be NTSC (my apologies, I keep mixing the two up, but I am 100% positive that is accurate now). This is why I kept having to reencode when I was burning.
I have since changed the TV Standard to NTSC (which is where it should be, right?)
Per your suggestion, I've been exporting a small clip of the footage thru Save as Disc Image (which is a god send btw haha). I played with the Field Dominance and tried exporting with each of the 4 options (Top, Bottom, Progressive, and Automatic) and saw no change in the video (there's a very noticeable improvement in the exported footage versus what I see when I watch the footage in Toast, however I'm still seeing the lines, just not as prominently and constantly). I also tried checking the "Half Pel" tab next to "Motion Estimation" just for the hell of it and that didn't appear to do anything either. I even exported with all Automatic settings and again saw no difference in the footage. Summary: all the footage exported looks the same, and though the quality is better than the preview in Toast, the exported footage still a few steps down from the footage when I open the .mov file in Quicktime.
What else do you think could be causing this?
By the way tsantee, thank you so much for all your help thus far! I don't know where I would be without you, and again I apologize for my mix ups. I'm still learning but I'm understanding this stuff a bit better now (I think/hope lol).