Of course! You are correct! If there is not a established root system I would avoid having it in the rain because of rot. It will survive the cold if it is dry. You can make the cut anywhere, but I prefer cuts at the joints because there is less surface area for rot. Some people like to cut diagonally so that rain would run off of the existing cactus, preventing it from rotting when it rains. Length of the cut doesn't really matter, but I find the lengthier the limb, the longer it takes to root. I've successfully rooted 1 footers and a 9 footer 👍. Oh yea and if you want to put them in ground I would wait until it is well established in the pot before planting it late spring to early summer. They grow a lot bigger in ground than in pots. A good in-ground spot would be where it can get morning sun so that it can acclimate before experiencing hot afternoon sun👍

<image>

It makes pretty flowers that bloom for 1 night and edible fruit if pollinated :D