Hello and welcome,
1 - You won't starve to death if you log out while in the settlement. Some more clarification about that here.
2 - No idea.
3 - No, once the game is out you will not be able to purchase anything higher than founder.
4 - Yes there won't be auction houses, people and npcs will have their shops, I assume some cities will have big markets and you can trade with people directly.
5 - What do you mean by safe spots? PvP can be done anywhere, but generally cities will be safe spots due to presence of guards in them, and when you go out in the world you shouldn't expect a gank fest. Personal guards will be used mostly by nobles or wealthy merchants, people who make a good target for a bandit attack, I doubt people will risk their spirit just to attack a random traveler.
6 - There will be always a risk, but there are options to minimize it - If you have a house you can store items there in locked chests or hidden safe, also people will have their banks/storage boxes available for rent, and I assume you will be able to rent a room in a tavern for example where you can keep your stuff while you stay there.