Newby player needs assistance with some of the game mechanics/things to do

TLTR - Needs advice on how to handle inventory and what to do in early chapter 2 (apart from doing marked missions)

I am a newby PC player - have spent several hours in game and I am currently t the beginning of chapter two. Went on my first free run outside the camp, but have some issue, hoping someone could clarify the mechanics

1. what is the difference between the core and the ring around it? Tonics are restoring the ring, while the core is restored with some food?
2. How's the whole hunting loot system working? So I shot the deer - put it on my horse. Then I have noticed another one. Since I am out of space I could only skin the second one - got venison and fur. Venison went to the bag - fut into my hand. I did not get hot to keep the fur. Had to leave it behind before mounting the horse
3. So I took the carcass to the cook guy in the camp - after dropping it on the ground I was auto taken to some outskirts of the camp for skinning. Do I leave it there and just take the meat to the cook?
4. How do I get those antlers/skulls and most notably furs from the animals I have killed?
5. I know I am very early in the game - but... what do you do while away from your camp? I run into some o'driscoll boys 50m away from my camp and just killed them. and ... nothing. No descent loot/no consequence - must be a filler to educate the gamer about random encounters like this. Just a thought - are these NPC's on patrol routes - can you trace them to their main camp? I cared to hide their bodies in the bushes since it all took place next to a rather busy highway. Not sure I will be bothered in the future though. Same goes for killing/robbing next to the camp - looks like a bad idea.
6. There is a train station and I have dynamite - I thought maybe I should try to rob it. But again not sure I will do it all by myself, plus it is next to the camp
7. Should I travel somewhere far to commit some crimes to get cash for the camp or just stick around since it is clearly a tutorial level still? However, what do I do - marked missions only? Any other ideas on raising cash?
8. other suggestions?

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Many thanks!