Thai women aren't a thing. There are 35 million women in Thailand and 35 million attitudes. There are many different cultures within Thailand. People from Chiang Mai are different from people from Buri Ram. People from Bangkok are going to have culturally unique beliefs that are different from Thais from Hat Yai. I see young Thais engaging in PDAs all over Bangkok. I'm sure that would be different from Muslim Thais in the south.
Is there one kind of American woman? Can you tell me whether American women enjoy public displays of affection? Is that the same for a Manhattan hipster chick and a Mormon living in Utah?
Your question(s) seem so overly naive that you might want to quit thinking with your dick a little bit and take a step back in terms of what you're getting yourself into. Maybe your first step would be to ask your fiancee. If you don't feel comfortable enough to have a conversation about how she feels about kissing in private, I'm not entirely sure you're ready to be engaged.