Upload & Sell: Off
Perhaps you should make it clear early on you are looking for tips, not giving them? Just a thought.
Can't help with specifics but I can't see the point of using a lens (or restricting tubes) you can only have wide open, and for macro. You are making it hard for yourself and your keeper rate is likely to be very low (discouraging), unless you are only going to do studio work of 'stationary' objects.
Have you looked at this http://www.fredmiranda.com/forum/topic/780820 and compare rigs to output.