[LMH]

Welcome to the forum! I can't answer any questions pertaining to OZ but I can tell you from experience that question 2 is yes! Probably everyone on this site has spent more money on their car than they planned to. Lots of little things that you add, change or want are never figured into the car in the beginning. And there will always be things you would have done differently if you had to do it over again. That's my experience.
Larry