Ps4 pubg and pubg mobile are developed and maintained by different studios. Tencent games for mobile and bluehole for ps4.
This is one of the reasons people play this game. It offers this type of realism which other games/battle royals dont. In pubg you have to be more aware and use your different sences to your advantage.
Exactly same with the above point.
I think we're all capable of following a person when deploying. This also coincides with my first point that both games are developed by diffferent studios.
1. You dont get to choose maps because not enough people play pubg on ps4 for bluehole to enable it. If they did then there woudlnt be full servers. furthermore, the only reason pubg mobile has so many different game modes as well as the option to pick the map you want to play is because more people play it. FUN FACT: There are more pubg mobile monthly players than the entire fortnite playerbase.
2. Different games, different studios. There are cosmetics/features one game might offer which the other doesnt thus making this not work.
4. This is something people have already asked to be implemented and it is now down to bluehole to make the decision or not. I doubt they will add it tho.