1). J-11 family fighters includes J-11, J-11A, J-11B, J-11BS, J-16, and so on. Their relationship is as follows:
Su-27SK -> J-11 -> J-11A -> J-11B -> J-11D
Su-27UBK -> J-11BS -> J-16
In PLAAF, J-16 plays the role as a bomb or missile truck, and also beats J-10C in "Golden Helmet"-2018 air combat competition.
2). There are only J-11B, J-16, and J-15 in production now. J-11B and J-16 use nothing from Russia, including engines and ammunition.
3). PLAAF buys Su-35SK, basically due to its engines. China always has a two-track strategy.
4). If Pakistan buys J-11 family fighters, Russia can get nothing from the deal.