3no, very easy to understand
obviously the last character make sense
5 it's hard for some like look up a phone number while it's easy if "up" only shows relevent to directions like "to walk up a hill"
to the former situation, I prefer to memorize it as a whole phrase
6 Is this what I've answered in the previous one?
-If the speed of speaking is too quick, I can't figure out anything. I think sometimes I may take a phrase as a whole, I may not care much about what exactly the preposition is.
-up to now, I think they are almost the same. When I am speaking or writing, I won't try to list them all and then pick one. I may just choose one by instinct.
-yes. just correct it and memorize the right answer.
8 I don't think it has much relationship between them.
if the preposition shows direction, I'll think it visually. if it shows "slang" use, I just memorize it as a phrase.
I think chinese is chinese, english is english, I don't want to build the connection. because if I try to translate english to chinese, it will hinder the speed of understanding.