Jane -
Re: 2012-1/2. The early 2012 models were carbureted - not fuel injected. They came out with the EFI for the engine mid-model year.....hence the "and a half" designation, just to make the differentiation.
Re: 10" vs. 12" diameter wheels. You're best to get advice and input from the dealer on that. I believe 12" wheels will cause clearance issues in the front wheel wells, either height-wise or the tires will scrub in the wheel wells when turning. You might be able to alleviate that with lower profile (shorter) tires. But again, I'd defer to the dealer's feedback. If nothing else - If they would tell you that the 12" wheels would be fine and you then wind up with a problem, they would undoubtedly resolve the issue for you since you made the selection based on their recommendation.
Bill
