Honestly, I just stumbled into Neutral affinity by making both decisions I wanted to make and ones I felt would lead to some sexy good times (see
here what my Major Choices were). Maybe for some people who make all choices in one direction or the other it would require planning for a Neutral playthrough, but for me it just came naturally.
Most changes to dialogue are so far minimal and they're occasionally accompanied by an alternate render or 2. Some choices will start to lead towards greater branching paths, but for the most part, you can do a lot on one path and then get go back once or twice on different paths to unlock all the content.
No. The 2 versions are incomaptible and Steam wil only receive the completed Season 2 which will likely when Episode 8 is done.
No incest. Period. Lynette is not related to Jill and that is not her in the picture. End of.