Why don't you use annotative blocks? And why don't your 'symbol' blocks have the same scale?
Regarding the issue: try adding the Xdata to the block definition instead of the block reference.
Explain more Metric or Imperial is important.
Description key sets, Alpha, Numeric or Alpha numeric .
Styles for Contours and alignments ?
Who supplied your CIV3D they should have given you a DWT to suit your place in the world already set up.
You cannot accurately snap to a POINT if you have not enabled NODE under OSNAPS.
Personally, I wouldn't use the POINT command. I would first do the required math. Next I would insert my "X" block at the intersection of two grid lines then I would move the block the required distance which can be input via your keyboard (make sure Orthomode is enabled). That will be the location of your contour interval. When you have all the spot elevations plotted you can draw a polyline from point-to-point followed by using the PEDIT command to FIT a curve to the polyline.