1) Awesome software, used it to make my first two frames and will stick
with it for #3.

2) I have an idea. I think being able to mark the location of the front
derailleur braze-on tab would be useful. Just being able to display the
measurement the user calculated would be great... but shimano also lists
guidelines for heights... so it could be automated to some extent. Maybe
enter the height of the slot and then it could give options for different
gear ranges and suggest a height.

http://www.peterverdone.com/wiki/index.php?title=File:Braze-on-derailure-postition-road-web.jpg

3) In case you haven't run across these, they might be interesting or
useful:
http://www.peterverdone.com/wiki/index.php?title=Shimano_Framebuilder_Info

Thanks again for making this incredible software, it's made my learning
process a lot easier.