Oh my yes. Get those things out of your house. Read my post in this thread, Post #4.
I don’t know how high to put that lamp. It’s going to depend on the wattage of the bulb and your coop a bit. Put the lamp in a corner then put a thermometer on the floor under the lamp to see what temperatures you are getting. If you think you’ll have 70 degrees at the coolest time of night you are good to go. Another very important consideration is that in the far corner, it should be no warmer than 90 degrees at the very most, 70 degrees max would be even better. In that small area too much heat during the day is just as dangerous as too little heat at night if not more so. Watch their behavior and let them tell you if they are too hot or too cold.
My 3’ x 6’ brooder is built in to the coop. I put chicks put there straight from the incubator in the heat of summer or even when it is below freezing in the winter. In the winter I keep one end toasty but the far end sometimes has ice in it in the morning. They stay where they are comfortable.
I’ve had chicks raised in my brooder and exposed to the cold go through overnight temperatures in the mid 20’s Fahrenheit before they were six weeks old with no supplemental heat. They were fully feathered out and acclimated by growing up in my outside brooder. It wasn’t a problem.
I’d suggest in about a week you give them access to that run during the day to start getting them acclimated. One potential problem, especially if your coop is elevated, is that they might not go back in at night. Mine normally don’t at first on my elevated coop, the coop on the ground isn’t a problem. The first nights mine normally huddle on the ground right under the door. I have to pick them up after it is really dark and physically put them inside each night until they get the message.
This sounds like it is not your first rodeo with chicks. I trust you have a larger coop ready for them. 14 chicks are going to quickly outgrow that 4x6 coop pretty fast.
Good luck on the pregnancy. My second grandchild, first grandson, is due early February.