What CodeAni said about past possessions is correct.

Since we don't yet have a trading system, I am willing to give a refund if you accidentally buy the wrong item. Just don't abuse the offer and say you accidently bought an item when you actually just no longer need it or something; if people start doing that, I'll stop giving refunds.

I see.

So, for the future, if user A gives user B an item, is it possible that the item disappears from user A's inventory and goes to user B ?
Also, if I use an item in a roleplay very briefly, do I still have to buy it ?
Like, let's say I picked up an axe and fought with it then it fell in the sea, do I still have to buy it ?

Not sure on question 1. I would guess yes, unless user A is still using the item in past threads. If that condition holds true, both users would need the item until such a time that one of them was no longer using it.

Question 2 and 3, there's no rule about using the environment of a thread. If you pick up an ax from a bandit your character slew in the course of the thread and then lose the ax in the course of the thread, that's fine. If you take said ax and suddenly start adventuring around with it or start the thread with that ax as if you own it without buying the item, that's not fine.

Alright, but what if it remains with me for a few posts, or I lose it later in the same thread, but not in the other threads ?

There's no way right now to give an item to another users. That's coming, but at present, if user A wants to give user B an item, and user B accepts, user B will need to buy said item.

I'm okay with user A not having the item to begin with, so long as the only time user A "owns" the item is for the purpose of giving it to user B. For example, my character Luthene was given a ring; I'd be user B in this situation, and I bought a ring for her, but since the ring-giver (user A) was only using the ring to give to to my character, he did not need to buy it.

If you pick up an item in the environment, it can stay with you for a few posts, but not across multiple threads nor should it leave the area. Related wiki article.

Oh, I see.
I see.
Alright, now about roleplaying money.
Is roleplaying money affected by server money ? Like, right now I have 366 server money, but does it affect how much money I have in a roleplay ?

The amount of silver you have on-hand doesn't necessarily impact the wealth of your character.

^ What Jenna said.

If anything, it would be more likely that your character could show off wealth with items, which makes some sense given that while one could say that their character is a very wealth person, they couldn't be living in a mansion or have the attire in rps if the items don't exist in their inventory.

Thanks !
Also, speaking of mansions, since we don't buy buildings in shops, I can live wherever, right ?
Like, my character can either be a nomad or live in a luxurious mansion or some cheap house, or on a farmland, true ?

As long as your character's dwelling doesn't offer them some sort of advantage when it comes to combat/etc., then they can pretty much live wherever.

It goes without saying, of course, that without the express permission of a deity, those realms are off limits for the location of your home/whatever it is your character lives in.