Taildragger (RV-7) or Tricycle (RV-7A)?
Tricycle. I have not flown a taildragger and don’t doubt that they are fun, but the choice was easy. Better ground handling and visibility, better short field performance, better crosswind performance and higher re-sale value.

Tip-up or Sliding canopy?
Tip-up. The slider is great on the ground as you can taxi with it open which would be nice on hot days however the tip-up has superior visibility and I’m building this plane to fly…not taxi. Also, the tip-up gives better access to behind the instrument panel which might be handy.

Primer?
Yes. Priming the whole inside of the aircraft. I live and fly in a coastal environment so the small weight and time penalty is worth it.  I’m using a 2-part Strontium Chromate Epoxy Primer. (Altra-Bond 3094 from Altex Coatings)