After spending some time in a Toronto court just watching the proceedings, I noticed that in pretty much all cases the plea bargain offers for speeding tickets were a reduction in speed over the limit. Would that be the case in the rest of Ontario, or are any jurisdictions willing to drop it down to a non-moving violation?

I heard that after receiving a speeding ticket in New York state, many people from Ontario easily get the charges dropped down to parking tickets, not sure though if that is a courtesy they extend to visitors only or to locals as well. Is anything like that possible in Ontario?

No, plea deals are almost always to a similar, related offence. I've never heard of them being dropped to a parking offence.

It would be unethical of a prosecutor to allow you to plead guilty to an offence that wasn't supported on the facts. When you hear about people pleading to different offences it is (or should be) because the offence they are now pleading to is ALSO supported on the facts that gave rise to the original charge. For example, running a red light and crashing may get you a careless charge but the facts would also support a plea to red light.