Can someone give me advice

I have raised chicks before and have had great success, however, I haven't raised chicks in over 2 years and ive never raised speckled sussex. These girls are currently in a tote about 3x2ft but they are growing quick. They are showing great feather production but ive only had them going on 2 weeks now. I know the rough time frame is about 6-8 weeks for full feather development. I live in southwest pa where the weather has been all over the place. 80 degrees today but I'm sure we will see a 35 degree day before long.

My concern is the tote being too small...the plan is/was to integrate them into my current coop (sectioned off of course) by end of april. I dont know if I have a full month of chick growth in their current state.

1) is their enclosure too small for just the 4 of them?

2) would it be a safer bet to run the heat lamp out to the coop and keep them outside?

I dont know when or if we will see a freezing night. Im not sure if the heat lamp in the coop would be sufficient for freezing temps.

Would love some advice for my babies