Congrats, I'm sure you'll like it.
I would have the liner or a waterproof over-jacket (my perference) with you on those 55°F mornings. Frankly, I'd freeze wearing mesh in 55° F weather, but then I don't really have any wind protection either.
In 20°F weather you'll want an extra layer or two under the jacket, but will be fine. An electric vest is nice, but not necessary ( I commuted year round for several years in NoVA without one and survived. This past winter was my first with one and I must admit I'm adicted:)).