I could translate the first example as:
Friend A: 우리 지금 출발 안하면 늦을 것 같아. John은 어디있어?
Friend B: 에이.. 좃까. 거기서 보겠지 뭐.
But, If I were Friend B, I'd just say: 에이.. 버려(abandon). 거기서 보겠지 뭐.
The first word has a sexual origin just like "fuck him". But for some reason, I feel the Korean counterpart is more offensive and I only use that among few very old friends. ...
Korean has formal and informal embedded in the grammar, much like most European languages with a T-V distinction but with more levels. Grammatically, there are quite a few "speech levels", from archaic Joseon-dynasty / Biblical [하소서체] to casual between friends or to children [해체]. However, I think most beginner Korean courses teach just two: 해요체 and 해체, with ...
The most commonly used expression for the verb "to smoke (a cigarette)" is (담배를) 피(우)다. Sometimes 담배를 태우다 is used too. In literary language, it appears in the form of 흡연하다. Also, very informally, 담배를 빨다 is used.
The difference between 피다 and 피우다 in this context is minor, although 담배를 피다 is not considered the standard.
As a side note, 연기 is the noun "smoke" ...
There are three common ones.
-(이)야? 네가 영훈이야? (Are you 영훈?)
-(이)니? 네가 영훈이니? (same)
-(이)냐? 네가 영훈이냐? (same)
-(이)야 is both an indicative and and interrogative form.
-(이)니 and -(이)냐 are interrogative only. -(이)니? sounds more casual and friendly, while -(이)냐? may sound a bit rougher, like talking down. Females tend to prefer the former and males the latter.
I'm going to interpret your question as "do native speakers use 요 with friends who are a few years older than them?".
The answer is "it varies". It depends on lots of different factors. I'll give a few of the most common factors involved, very rough order of importance, it really much differs from person to person and situation to ...