Personally, I think these Skylanders are trapped inside vehicles/engines, in the same way that a genie is trapped inside a bottle, allowing you to switch between vehicle mode and Skylander mode on the fly as the game requires. I think that's the gimmick.
Also, in regards to the late reveal, I distinctly remember lots of people moaning about Activision not showing enough regular content between reveal and release last year. That happens when the dates are too far apart. They probably felt they wanted a shorter window to maximise the marketing noise from their reveals. It also allows them to assess the opposition and steal some of their thunder.
Exactly what I was thinking. In SSF, we went for MONTHS without any reveals until a Star Strike picture leaked. In STT we had info a lot more often, and this time well have info even MORE often.