Agreed. Math, for the most part, is very rule oriented and problems only have one answer and often one strategy to get to the answer. If you work on many different problems (in the same subject) you should start to get used to the rules.
Overall I would say a strong math foundation is important to CS but CS isn’t just about coding. You can absolutely get a coding job without strong math skills or even without a degree, it’s just a bit harder to get started. If the discipline still exists you might consider a Business Information Systems degree (we used to call it CS lite). Depending on the position a company might equally consider BIS and CS majors.
If the laptop supports dual drives (not unheard of but not the norm) it’s way safer to dual boot from different physical drives.
Whatever OS you choose make sure they have a guide for dual-booting. Any Linux OS should be capable of dual-boot but not all will support that configuration equally.
As a failsafe I would also make a rescue USB, especially SystemRescue because of the findroot option.