Yes, some information could be better organized. Team Khadas is working to improve the continuity of info.
An excerpt with some connector info from khadas.com/vim…
As seen in the schematic, UART is contained within the 40 pin GPIO…
Sorry, cannot help with the DVB hat, do not have one. Wish they had ATSC version. 
You may want to pose your DVB(VTV) questions over here.
Cheers.