Hello! I'm new

I live about 20 minutes north of Green Bay and just got my very first 6 chicks today! 2 'red pullets' and 4 straight run buff orpingtons. I really wanted buff orpingtons but since I'm after females I decided I'd only chance it with 4 of them and go for 2 that were definitely hens! I'll probably be back at Tractor Supply before the end of the week for more

they said they got the pullets and orps in this morning but that they were expecting more. How old is too old to introduce new chicks? Would the first two weeks be okay? I really wanted to get 2 silkies since my daughters fell in love with those but they didn't have any so now I'm on a mission to try and find some (they want black if anyone knows of any chicks in this area, or even fertile eggs would be great).
I'll have to get some pictures of the pullets up to get some guesses on breeds, they both look different from each other for sure. I told my husband I was just going to get 6 hens...he'll be surprised when he gets home tonight.
Do you all keep your brooder in your house? Right now our 'guinea pig cage brooder' is in our dining room so the kids could watch the chicks today (and they've spent most of the day right next to it!) but I was thinking of moving it to the basement or garage, would the heat lamp keep them warm enough?