In the episode where Radar believes he's hit the old Korean with the jeep, his friends convince him at the end that it was all a scam. But then they each chip in a few bucks to pay off the old man. I believe Radar even asked for the money! Why? Seems pretty ridiculous to give in to a scam, when you know it's a scam!
Did Trapper and Hawkeye (later BJ) 'like' Frank? I think they had an 'ok' relationship. They acted friendly amongst each other to some degree. But in other episodes, they were downright mean to each other and Hawkeye even punched Frank in the face (and Frank had Hawkeye court martialed).
I don't think BJ and Hawkeye liked Frank as much as they liked Winchester, though.
Frank was shown or implied to have a lot of money. This is speculation, but do you think he had as much as Winchester? I'm thinking Winchester was supposed to be the more wealthy person, but I don't know.
My answers to your questions are soley based on my opinion.
Keep in mind that most of the doctors & nurses that worked at M*A*S*H felt bad for the Korean people & new that they were struggling to survive due to the war. They realzed that "Whiplash Wang" was sacrificing his body to get money. That's why they took up the collection.
Hawkeye & Trapper & then BJ really didn't care for Frank as both a person & a doctor. At least Charles was a good doctor.
Frank may have had some money since he went right into private practice. The other doctors worked in hospitals. Cahrles was by far the wealthiest due to his family having an enormous amount of money.
Hope this helps.
Yours in M*A*S*H,