For the Classic space guys, the helmet isn't exact right one of course, but I don't know if/when I will ever make a classic helmet too, sorry... ( But I think for the paper model, it's okay to use the "modern" helmet. And for the Blacktron I guy, the helmet is perfect, with the black visor! ;o)
The only comment I have, is that I didn't find any files for the yellow and green versions in the Super Space Pack...? Maybe it was a corrupted download for me (I haven't tried again) but maybe you can check it? Sometimes I put the wrong files in the ZIP file too, it's an easy mistake to make if you have to ZIP so many files ;o)
It takes a little bit more time to build the lineless version, but if you're careful enough to compare it with the version with lines, you can work out where you need to score and fold it, and then it's basically the same of course. ;o)
But I saw the lined version in your gallery, and I think it looks pretty good too! I think it kinda makes him look extra "cartoonish", which fits him very well!
You never know if you try. So what if you only make one part a day, and forget about it for months and only work on it again when you can't think of anything else to do? There's no rule saying you have to finish it in one go or within a set amount of time. ;o)
Do you mean designing it or building it? Making the 3D model ready for papercraft, unfolding it, testbuilding it, fixing the mistakes, finalizing the design, building and making instructions and then finally releasing it, took me several weeks, but I had a lot more spare time back then... Actually building would probably only takes a couple of days, a couple of hours each day, with cutting out the parts being the most time consuming part... ;o)