Joe,
a. how do I put some contour line labels in towards the center of the plot (see pic)...?
The short version is you can't. Your plot exposes a weakness in the routine used to pick label placement. Each contour value is labeled up to 3 times. The label locations are selected so as to a) maximize the distance between the 3 labels and b) not overlap any other labels. With this plot that set of rules leads to labels placed mostly in the corners. I'll have to think on this one a bit.
b. how do I align the contour labels in a straight line (say vertically)...?
No way to do that either, sorry. I can fairly easily add an option to place all labels at X or Y = some constant.
d. how do I remove the outside tick marks on the x and y axes...?
Other than not drawing the axes at all (which I understand is not what you want), you can't. I need to add the same tick mark options available for XY plots to the 3D stuff.
Is there a way to change the color of the x and y axes...?
Finally, yes, there's a good answer for this one
Under Options>Contour Options click the Axes control in the Colors group box (towards the lower right of that dialog).