Good. And as suspected!
You can install that with:
sudo apt install smartmontools
Its only to give some idea of the state of the disk, as from some of the comments above, it could be the culprit for the freezing, although failing/worn intermittent cables can wreak havoc as well. TBH, not sure if SMART works with external disks over USB, although AFAIK its a feature of the disk controller rather then the connecting technology.
If you can afford it, it would be better to upgrade the laptop with an SSD with adequate capacity to install both operating systems. While its understandable trying to make the most of the resources you have, it would run a LOT faster than trying to boot an OS from an external drive over USB.