Good lists here. Essential pieces of equipment for me include:
- Arm warmers (especially for morning/evening rides with temperature variations)
- Wind jacket (easy to pack, for when arm warmers aren't enough)
- Wool base layer to wear under jersey (for me, if it's not going above 55F)
- Wool socks
- Soft shell jacket (for 40F and below).

I'm considering getting some knee warmers. Honestly, though, I have no problem just putting some fleece long underwear on over my shorts if it's not going to be warm. I don't worry too much about hands until somewhere in the 30s F - that tingle means that you are still alive!

Also skinny with a low heart rate, but I don't tend to get cold easily. The family kept complaining when I tried to keep the house at 62 all winter. I'm also from Michigan