I'm quite sure you can do both in all camps. Cope's camp was still pretty pointless despite that. The nitro you get from his place isn't even good enough to let you jump far enough for the NERO sites.
No you can't. Some weapons droped by A.I can't be stored. In the early games you can just count with your pistol, melee attacks or weapons by enemies with can't be stored.
You need to advance to the next camp for buy weapons and
those weapons yes you can store, but we're here talking about Copeland camp.
Anything you buy, is always available from every locker. Be they in NERO outposts, bunkers or camps.
The reality is that early on all you need is a pistol and the crossbow on any difficulty, because you are supposed to be evading hordes at that stage. Focus on ambush camps and outposts to buff yourself up, and work mainly on improving your bike.
Until you reach Lost Lake its mainly about scavenging and gearing up for the ride.
Sigh... again people keep telling this over, over and over again. I even surprised if someone really play the game or saw the story. You know the Deacon beat hordes before the initial plot don't you? He have being doing this for survive as much he can. Don't make much sense, aside from the 'bike' problem in the early of the game. As you can see, its easy beat hordes with a handgun.
Don't get me wrong, Days Gone is one of my favorite games this year, but some arguments really don't make much sense for someone like me with spend so much time in this game. If Copeland can't sell guys at least give you the option to store the weapons you get from the other bikers.
Btw, you reach the Hot Springs Camp more early than Lost Lake just by making the story mission.