So to call the witch to the arena, i need to do all the talking and also the golem quest to unlock her ?
Maybe? I have no idea what else you have or have not done in the game. If you are trying to start a brand new game and jump straight to getting the witch in the arena, it might not work.
When I referenced my issue, I had gone through pretty much all of the content up to that version (0.9.15) and when I started my game in the new version (0.9.18), some of the quests had reset, without any indications other than missing NPCs, and I had to redo some of the quests involving the town and the Politics quest, before I could free Shorca and start the arena area with the witch.
And also does this unlock the potion thingy on the chair or something from what i read throughout all the post ?
I am not sure what potion you are talking about. It could be a quest I did not do or one that I ignored. It could also be an item that is tied to another quest, that was possibly reset. This is assuming that you are coming from an older save into a newer version of the game.
If you are having problems trying to start/complete that quest (or other quests), you might want to just start a new game.