While I liked the four seasons per year of STW, I think the two seasons per year for RTW was best.

MTW having three eras, though they were one year per turn IIRC, felt right to me.

By going with three eras M2TW could have gotten away with two seasons per turn. However CA wanted to give players the medieval experience so they made compromises.

I seriously hope that the first patch will include tools that make modding M2TW easier. Beyond this I seriously hope that CA or one of the community's more skilled members, like V, will make it possible to modify and add new units.

Honestly, though many months away, community mods are probably our best bet along with another patch or two from CA.