question1 :"I wonder how 打扮, (to dress / make up), came about?"
from a Chinese language Dictionary:
It combines with a transitive verb to form a paratactic structure. The function of "打" is to generalize the meaning of the combined verb. for example :
There are 20 meanings of the word "打". "打酱油" should take the 6th meaning, which is 举，提起。Per to Toosky's answer, "you need to go to the shop and ladle it into your container" ladle is the action of put the soy into the container and then lift the bottle. Namely, 举，提起. That's why we call the process 打酱油
打 in 打酱油 doesn't intrinsically mean "buy". In the last century, soy sauce was not sold in bottles as today. It was produced by the merchant himself, so you need to go to the shop and ladle it into your container from a big jar. 打 is for the action to lift liquid from a jar or well with long spoon / bucket etc. SO IT DOENSN'T MEAN “BUY” ELSEWHERE.