Phil,
I used the AUX input (not MIC) to the soundcard - straight in. PC soundcard oscilloscopes also use that input. Hopefully your mileage won't vary, but I've never had a problem.
I can't say for sure how fast the CM17A will transmit. My guess is that it might be faster since it takes commands quickly. On the other hand, it may repeat commands 3X when it sends. But this is all just a guess.
Good luck on getting your stuff going. It should just work at close range without tuning - at least that was my experience.