Imports:Making Animations Basics

Blender

Only 4 weighted bone assignments per vertex. If you have more, ogre will eliminate the lowest weighted one. Means: only four bones can affect a vertex (sliver of skin). Fe. I have a tattoo on the back of my hand. Moving the fingers can make the tattoo dance. Moving the thumb will not.
All vertices must be assigned to at least one bone - assign vertices that do not need to move to the Bip01.
Each bone must have a keyframe at the beginning and at the end of the animation strip.
Use unique animation strip names. I mean it. Have fe. your own nominator. I, myself, have CBT at the beginning of my strip names. In that way if I make a chair that uses my basic sit 'CBTbasicSit' I know the game will call MY basic sit and not any of the dozen basic sits other modders have made. The more furniture makers there are, the more likely it is that two or more of you will use the same generic name for the animation. You spent hours making the animation, you should make sure your subber will see your hard work :)
Do not edit or replace the main animation skeletons unless you are making an animation overhaul. 90% of other mods in the workshop rely on the vanilla basic animations. If you need to replace one animation in the vanilla skeleton, just make a new skeleton with just that one animation with the literal same strip name the vanilla skeleton does and add that to all races you want to alter. It would be good if the replacement you make would work in its vanilla purpose ie. no point replacing vanilla animation if you do not want it to be called whenever the vanilla one was. Also of any other mod is loaded after your mod in the game, the vanilla skeletons are replaced back. This is why it is recommended to just have your own animation file and just add that to every race. At least the mod loading order does not affect your mod.

FCS

An animation file must be assigned to each sub-race you want to be able to use it. Common ones like sits and sleeps on furniture should go to all playable races. This also means a patch is required for each additional race in the workshop (if you want them to be able to use your anim).
Having the animations in the vanilla file patch formation is strongly suggested. If a computer quip is to happen and Kenshi forgets what it was playing it will look the animation from the male_skeleton or female_skeleton folders. If the animation is not there, it can crash.
Yes, female and male skeletons are similar enough for some static poses to work for both. But if any movement is involved, make a separate skeleton for both.