Nestor will never be in any relationship toward the very end of the game. So there is no “netorase” is this game. However, a hint of netorase is in the game when Ferra reciprocated his feelings but the player insists on letting her “go wild” with Kota. It can’t be called Netorase since Ferra does not belong to Nestor to begin with. But it’s debatable.

One of the achievements is to “prevent” all NTR events in the game which will reward player with secrets. This has not been implemented. So it is completely avoidable but you don’t get to see many  h-scenes  if not none. 

This link explains it well in Japanese. For short, it stands for "Boku ga Saki ni Suk datta no ni" , which loosely translates to "Even though I loved her first". BSS is basically the theme of the canonical storyline. It isn’t conventional but I always think of this game as a subgenre of BSS called “silly friend’s BSS“ where the antagonist is just a simple nincompoop.

Make sure you have the right settings  when you choose “option “ in the title screen.  Somehow, some players have the game set to skip by accident.

You can always return to the hub from any quest. Once you perform an action, instead of "End tern", choose "Options" and "Return to the hub".

For the female party member, yes. They will wander on their own. You can order them to go to places or attack enemies.  For Kota, he has his own lust mechanics which increase every turn. If it reaches a threshold, he will start pursuing the closest available female party member. So your job is to find your own solution to complete each quest. You can order every party member to keep them occupied. You can let them do their own "things". Or you can try to finish the quest yourself but occasionally interrupt Kota's misdemeanor.

 “Pregnancy” is one of several “unfamiliar kink”. All dialogues and scenes in this game are based on our familiarity with certain kinks and theme. If we (the devs) are unfamiliar, or uncomfortable with any particular kinks, we can these kinks “unfamiliar”. Rather than writing half-ass dialogues on the kinks, we don’t incorporate them into the game entirely until we figure out how to develop cohesive dialogues.

It's one of the prominent kinks in this game, but it is totally missable. 

No. SRPG only supports window only.

 The game lets you bonds with the girls but talking to them in each quest. You have to talk to them once (you will see unique dialogue) and complete that quest. In Ramaluq, you can buy certain items to raise Ferra’s bond as well.