How can I achieve sets of concentric arcs shown here: http://pics.nexuizninjaz.com/images/54o ... xzmg3l.png
Is there a simple way to do this?

Yes, there are actually multiple simple ways to do this. My suggestion is using pattern along path live path effects.
1. Make your ellipse (the gold one) your basic shape.
2. Draw the shape used for the individual pieces on the gray arc behind the gold ellipse. Use that shape as the pattern along the gold ellipse. Play with the spacing of the pattern to get the effect you want. Probably best to use the repeated, stretched option.
3. Do the same thing for a smaller concentric ellipse with the triangle.
4. Finally a smaller ellipse with a fill for the dot in the middle.

I would just use circles of different sizes, use Shift and Ctrl while drawing and snap to center to draw them concentric right from the start. For the outside one I'd use a stroke with dashes or draw white rays to cover circles (because of the angles).