As for initial research of Naval Kits, that is a whole different conversation that YOU were not discussing in your previous posts above. At least as it relates to the research done on these two kits of the same subject, both firms at least came up close on the length.
The Chinese Plastic Model companies research on Naval subjects. What research? Typically they buy a resin kit of a subject and copy it, warts and all. It isn't like they are banned from going to the the US National Archives (for USN subjects) and getting the drawings and details for very little cost. It takes time to dig out the information however. Buying someone else's "research" is easier.
As far as I have noted in my years of building Plastic kits, Styrene of various grades is used. Some parts have/are made with vinyl for specialized applications. Styrene is easy to glue and works well with filling in fine detail.