Hi
@Voithe! Thanks for the nice words <3
1) If you export with the pose, it should import fine. Make sure to use a recent Timeline version, and make sure the animation you want to expert is indeed IN Timeline, and not using the Scene Animations
2) Yes, you could toggle Loop, and then delete a few frames in the end (in More, Bulk you can do it... in bulk) and it'll do a smooth transition. It's not magic though, so you might have to tweak that a little.
3) It'll probably ruin your whole neighborhood. If you don't care much about your neighbors, you can try, I think it's going to be fine if you don't have parenting, try and see

4) You need to select which targets to reduce in the dope sheet (the list of targets on the left)
5) Audio sync means it will sync the Timeline animation with the audio. Even if you play the audio slower, Timeline will play slower, etc. So, the audio and Timeline will always match, it's by design.
I hope this will help you!