HI Cal,
To answer your question about time, that really varies from person to person. Some folks take a long time to do things because of time they can afford or due to precision-work, etc. Others like me, once they have the parts, run with it and make it a whirlwind. I tend to do things in ten minute increments in between all of the other things I have going on in real life. It is really up to the person, their experience level, and what sort of time they afford to the project. Potentially a scout could be done in a couple of days or it could be a few months.
As for the boots, the first choice is clearly better. The sole is a big part of the scout. Even those would require some simple but time-consuming razor work on the soles to look accurate. They are a great base though and are similar to what I used.
As for the flightsuit, I recommend avoiding military suits as they have too many pockets and zippers. What many of use is a racing jumpsuit from Redkap. They are super affordable, fit better generally-speaking, and have nothing you have to remove or hide.
I hope that helps.