I think Vietnamese are becoming more Democratic with each generation, similar to cubans. They are still a Republican demographic though. It also depends where they live. Those living in Orange county seem to be hardcore Republicans but those living in San Jose and the PacNW are split in their voting.
This is also true. And not surprising. As their children assimilate, it's only natural their voting patterns would trend towards the mean.
Also, voting statistics for Chinese are completely useless. Because you have people who came over from Taiwan in the 80's, people who came from Guangdong in the 1800's, people who fled Hong Kong before the handover, people who moved from the PRC in the 90's, and literally 500 different groups, all who are very very different. As opposed to say Vietnamese or Cubans, who mostly moved to the USA in two waves.