Oh, that choice has nothing to do with the personality description changing. It actually changes in the scene before you make that choice about how MC reacts, and even then it only changes depending on other choices you have made throughout the story. I checked and I don't see anything that could be bugged about it, so I think unless there's something wrong with your safe file, it is working as intended.
Now to your questions:
2) The main story will be released on itch for free. However, there will be some epilogue chapters (mainly focusing on romance) that will be exclusive to Patreon and/or paid DLC. I want to strike a balance between everyone being able to reach an ending to their story, while also providing something more for those that are willing to spend some money on it.
3) The personality stats serve two functions. They change some of the flavour text about your character, and they are relevant to get certain endings. However, they never determine which choices you can take, for example, a dishonest person can choose to tell the truth, or an honest person can choose to lie. So in your example, no, the stat has nothing to do with that choice.
The relationship stats are more important. They determine which routes you can go down, which factions you can align yourself with, who you can form a partnership with, and more.
Aside from personality and relationship stats there are also a few hidden stats, but they're hidden for a reason.