Opinions and answers to both of your questions can be found in the threads "Civ 3 or SMAX?" and "A cry for help!" respectively. I bumped the later for your benefit. The consensus seems to be that many SMAC fans are dissatisfied with Civ's lateral evolution path, failing to take advantage of many of SMAC's spearheaded features. It's biggest saving grace seems to be superior tactical AI.
Personally, I snagged my copy of SMAX at a used computer game store; you may want to give such places a go, if you haven't already.
Otherwise, enjoying lurking on Chiron. Carry on, talent.