What is the difference with respect to 미안합니다?
좌송하다 is more formal/polite than 미안하다.
I've heard 사과합니다 used in k-dramas when someone has made a huge mistake. Is that more formal than 죄송합니다? Does it express a deeper regret?
Sagwa means apology (as well as apple) so I assume it means I apologize, rather than Im sorry?
I see what you did there
Would "excuse me" not work?
No. Both "I'm sorry" are used for apologizing for a fault. You could use it when you bump into someone but not to get someone's attention and not to express saddness for someone (eg. I'm sorry to hear that)
How do you pronounce it?
Kind of like Jisung
Jwe sung (not the exact romanization)
wouldnt this also work as " I'm sorry" or "I am"
I am sorry