About honorific infix (으)시 and imperative form -세요
Hi~^^
I have some questions because I am having a hard time with honorifics...
I am learning about the korean honorific infix and that it's supposed to be for when you are talking to someone about someone you are supposed to use honorifics for. But I'm wondering, what if you are talking about someone of higher social status or older than you to someone who is older or higher than this person? I think I read somewhere that it was for exemple impolite to use honorific for someone of your family when talking to your parents in-laws... I think...
Also, I have another completely different question:
How can you see the difference between (picking two random verbs) 사다 (to buy) and 살다 (to live) ? I mean when the ㄹ at the end of the verb is supposed to disappear, then it's 삽니다 / 사세요 / etc for the two ?
Also, about the imperative form -세요...what if you are talking to a friend/a kid and you don't need to use respect?
I know it's a lot of questions, but if you have a little time to help me, it would be amazing ☺🙏
Thank you!