Glad to hear that you are making progress. Are you printing the new v2 versions I loaded today? It sounds to me like you may need to either dial down your flow rate or your temperature. or both. I had trouble printing small tolerance pieces until I made both of those adjustments. It could also be the first layer getting squished enough to touch the other parts.
I have been designing my parts using Tinkercad. It is a free online design tool. I started using that because it was the only designing tool that did not cripple my old slow computer. Now that I have a faster computer, I have not taken the time to get used to any other modeling tool. Tinkercad is a powerful tool that has many features that make it user friendly and it functionally has a design resolution to .1mm. In my Little Digger object description you can find a link to the Little Digger in Tinkercad. You can copy it there and take it apart or modify it to see how the different parts were designed.
I also have been modeling in Sculptris. I have nearly completed a T-rex skeleton that I am getting ready to prep for 3d printing and some interesting stuff. You can see that one here: http://www.thingiverse.com/thing:342051
$90 an hour... you must be working from home on the internet in your spare time to make that kind of money.