I have a few questions right now.  No answers.  Sorry.
Have you decided on a covering material yet?  Or, if fabric, the method to seal and paint? 
How bout radio, servos, Control rods, linkages, engine size and type? 
You definatley seem to be on the right track so far.  I just know if you have had thoughts about the detail work in building your own.   What you need to know (if you dont already) Is that the larger structures will go together kinda fast in comparison to the detail stuff.  And how long that goes depends on answers to the previous questions. 
Another question.  Have you tried any flt sim?  I have RealFlight and I love it.  I am not at home right now so I cant confirm it but I think the base software has the Extra as one of the standard a/c available to practice on.  Flying that a/c on my sim is a blast.  Definatly makes me want one.  I need to get better as a pilot before I try my hand at a plane with those aerobatic capabilities.
I start my model build with a written checklist of everything I can think of that I will need to buy or build, in order to complete the project.    I then inventory available stuff already in my shop.  From there I can actually set a budget.  But I dont.  HAHaHa.  Im gonna buy this stuff.  All I try to do is find the best deal on whatever I am looking for.  If I had a real budget I could not stay within it!  
I do use the checklist tho just to understand the scope of the job.  
Looking forward to reading your answers. and I hope you intend to build thread with pics.  See ya.