Thanks for that link, much appreciated!
I find when sewing leather that spray adhesive is your friend. It keeps the piece in place just enough so you can skip the pins and run your stitch with precision.
I modded the RedKap coveralls for my Fett and X-Wing Pilot flightsuits and they're both pretty dang comfy. I plan to do the same for my scout since they're just so simply constructed and perfect for modifying. The military ones all seem to have double or triple secured seams and complex zip pockets that are a pain to take apart, especially if you need to put the seams back together after your modify the suit.
I would recommend at least a light level of weathering to make the costume feel lived in. At the very least it will keep it from looking like an off the shelf costume or make you look like you've never seen any action. To me, everything in Star Wars is old and dirty and used though so take that with a grain of salt. I like my costumes pretty filthy.
The boots look really good to me, though I'm of course just doing my initial research.
Also, good to see you over here, Lou! Didn't know you had a scout as well.