Should I study Hangul sound change rules?
I think so. It is essential to be able to read 한글. It’s not that difficult!
It’s an important part of Korean, but doesn’t really need to be a huge part of your studying.
Read through the rules (there aren’t that many of them) and learn a couple words that serve as examples for each rule (e.g 같이→"가치"). Then as you keep learning and listening, you’ll naturally run across more examples that reinforce the rules you’ve already skimmed, and they’ll become more familiar with exposure.
Does this mean you’ve finally chosen a language to learn?