Very nice job on the incubator. But you should know, a while back someone posted a warning
about rough service bulbs. They are coated with Teflon and it gases off fumes that are
toxic to chickens.
No you don't need to heat your coop. What I use for water, is a metal base heater purchased at Fleet Farm. Each of my coops has one.
In past years I would replace the frozen water a couple times a day. Glad I don't have that anymore.
The most trouble free I've used, is a metal base heater. They have a factory set thermostat only
turns on when needed. They cost around $40 dollars but last for years. Here in Minnesota we
have alot -0 temps and with these I don't worry.