Yes, the "Chamber of Lament" Is located in the Everfall, It's entrance differs from the rest of the chambers so it is quite noticable :)

I meant it as unlimited amount of times, and  yea you can teleport to the port crystal to go pick it up and take it to another location :)

He is located in the everfall dungeons in the "Chamber of Lambent". You can tell which one it is as the entrance differs from the rest thanks to it looking like a broken bridge. When you start a new game+ If you are in cassardis when you are looking towards the ocean take a right while on the beach and you should see a purple riftstone in a cove. 

port crystals act as destination markers for where ferrystones take you. To use it go to a location that would take a long time to walk towards such as right outside the bluemoon tower and go into your inventory and place it down. Portcrystals can be used multiple times while ferrystones can only be used once. 

P.S. it is not worth making a forgery of the item as when you start a new game+ they will become available to you for purchase at the Black cat

It works well with a healer mage, as if your being attack they focus on healing and protecting you. for example, When i was fighting a drake while i was in combat my pawn focus on attacking with frigor but when i was injured she focus on healing me

They may have had the guardian inclination which means they would only attack enemies that attack you, When looking for someone to tank or be a damager try to look for one that has  Scather, Challenger and or migitator inclinations

Nothing really game-changing, just save them :)

Stand close to the cell door, a guard should walk by it within a minute or two and you got to bribe him when he does. It is 5000 gold I believe

Your first playthrough will last 60 to 80 hours, if you could play dark souls than the difficulty in the beginning would feel normal and then it will become laughable on how easy it is, so if you just want a challenging game Than i assume dark souls should be your choice but the combat  and boss fights in this game are THE BEST I have ever experience in a game  

have you check your options, to see if your connectivety is on "online", if it is offline you will only be getting rift crystals from the game itself and not from real people using your pawn.