Will the 3G SIM card from my original 2010 iPad work in the new 2012 iPad, or will I need a new SIM card? I have the original 2010 iPad 3G, and when I purchased it I also got a SIM card for Rogers 3G data service here in Canada.

Can I simply remove the 3G SIM card from my original 2010 iPad, and insert it into my new 2012 iPad when it arrives?  i.e. is it compatible and will my data plan continue to operate as before, but on the new iPad?

Then, even if it is compatible, is there an advantage to getting a new SIM card? Are there data features for the new iPad (e.g. higher speed?) only enabled by a new SIM card?
This will depend largely on your carrier. If they're offering 4G/LTE service with the iPad 3, you may need a new SIM card. If they're not offering that service in your area, it shouldn't matter if you have a new SIM card or not. Your best bet is to ask your carrier.