Welcome To BYC
I was curious as to why you are only going to have them for a couple of weeks, your intro gave me a clue.
I ask a lot of questions, this is how I learn, I'm also a bit nosey if you must know that too

, so I'm not needling you, just asking and curious.
You got chicks, I assume as a present for Christmas? Does your girl have a place to keep chicks - coop/run? Does she have any experience with raising chick(en)s?
Where are you going to place the brooder, can you post a pic? Is the brooder somewhere out of the wind/elements?
If you are getting day old chicks, they need to have a space that is secure from predators. In winter, they need protection from wind and drafts especially. Warm side of the brooder start at 90-95F, cool side where water and feed is kept can be cold. I've had chicks outside at those temps you mention, but you must check on chicks frequently to ensure water is not frozen and they are eating/drinking well, getting under the heat to warm up, etc.
If the lamp is strong and keeps the brooder warm, then the heating pad may not be needed, but keep it handy just in case there's a failure of the lamp or...whatever, it's nice to have a backup.
https://www.backyardchickens.com/threads/new-here.1646761/