[quote=@DracoLunaris]
Are there any particular rules/guidelines to who the Kindred Spirit characters should be or is it or of a "npcs I would like to see" request list kind of deal?
[/quote]

There's no real restriction, but a character with a close bond to your character (such as a partner or good friend) is more likely to appear.

[quote=@ProPro]
Spoiler
[/quote]

Maybe. I haven't put too much effort into planning endgame story in just the interest check.

[quote=@Archmage MC]
Hm... can I combine or retool a few characters or no? Or do I have to RP as that character?
[/quote]

You can make slight changes if necessary, or expound a bit on a character that would otherwise be too shallow but generally you should aim to be true to your chosen character.