[Cgyracer]

Dimple on the inside usually..............for traction I don't worry about the dimple as it's on the inside of the tire.  If it's there it's there.   Some NSR tires fit better though (only select model of NSR tires & 12mm & 13mm CBD Hubs) with the dimple on the outside (check inside / outside hub fitment) and make sure the profile is tall enough in order for you to be able to true down to eliminate the dimple / irregularities as it is the outside of the tire that will be taking the full cornering load. 

You can sand any sidewall irregularities as you have pictured.   Don't forget to sand both directions by reversing polarity to eliminate any "feathering".  I have aluminum "sticks" with various types of grit glued on for sidewall grinding.   Lighter fluid works well on the sidewall to smooth the surface if you had to grind down the sidewall.  

I have tried various brands of rubber tires and so far the non EVO tires are my favorite.

Just my opinion regarding NSR sidewalls.
Rob