I know exactly what you mean about Koong Nang, and she doesn't improve much in this one. At least in the old version, she wanted a less sheltered life (which is why she wanted the switch in the first place), and her stupidity stemmed from believing that everyone is a good person. Even then, she was able to pick up on who meant her well and who didn't, but in this one, she's even more clueless. She's so helpless and relies on Korn so much and cries at everything, but I never get the sense that she can read anyone or understand their motives. I really, really can't imagine how she'll survive once they switch. I'm still tuning in only to see Korn's reaction to Pak Boong when they finally switch. So far, he's just been the caring, supportive, older brother type. I want to see his reactions when Pak Boong starts messing up his orderly life and needs him less to save her.
As for Vee's character and Pak Boong, I believe there was some attractipon, but ultimately, he preferred her ladylike. He certainly harped on her enough on being less of a tomboy that I could see why he and Pak Boong would have never worked out. As for Pak Boong, given her background, she was more attracted to the gentlemen type, which all worked out for the best.
I seriously can't stand how they focus the lakorn on such trivial scenes and dialogue. I thought it was bad in the first version, but it's especially horrible in this new one. They need to spend less time on the side characters and focus more on the twins/storyline.