Guns of Infinity - Questions

Hey everyone, I was following a guide for guns of infinity from steam and came across this line

"A Knighted character has the chance to support the Hunter Wolfswoods with word/deed. Any repercussions are reserved for the third game."

1. What exactly are the repercussions in the third game?
2. I also saw multiple posts advising not to do the secret mission but without much explanation. Why is that?
3. I also saw like selecting brother and sister have them exist in 3rd game in guide so like do they do something bad or its chill?
4. I would also like to know decisions which might have some repercussion in third game?
5. Any other tips are also welcome

Thank You in advance