1. 석 달 is as same as '세 달'. For '4' , you can say '넉'. For 1 and 2 , we just say 하나, 둘 ( 한, 두 before a counter).
'석', '넉' is used with counters such as '잔 (glass)', '장(sheet)'.
'서', '너' is used with counters such as '말 (Korean unit of measure for grain)', '돈 (unit of measure for gold)'.
2. '주사' might mean 'drinking habit'. I guess '꽤 멋진 주사' means 'quite a cool drinking habit'. I just assume the meaning of 주사 as 'drinking habit' because it only fits to your sentence.
3. '퍽도' is usually used to be sarcastic for a certain situation.
'퍽도 없다' is used to emphasize "There is something or you found something even if the other person said you wouldn't find it."
e.g. A : 냉장고에 아무 것도 없어. (There is nothing in the fridge.)
B found a cake in the fridge and said to A.
B : 퍽도 없다.
4. 창의적이다 and 독창적이다 both mean 'to be creative'.
5. 살림차리다 means 'to settle a home with a boyfriend/ a girlfriend.'
'리틀 포레스트' 는 저도 좋아하는 영화예요. :)