Hello, what have been known so far about the alchemy ? I didnt like the alchemy/crafting in TW2..
Here's a (long) thread dedicated to alchemy:
http://forums.cdprojektred.com/threads/28983-The-Witcher-3-Alchemy-System
So we collect ingredients, get formulas, sit at bonfire, brew the potion yea ?
Yep, the core is the same.
What is this I heard about automatic filling of potions ???
The whole topic is still a bit unclear. Kinley, a forum member, interviewed the devs about it:
About the potion system - in a recent interview Konrad told us that the potions would auto-refill. Is this still the case?
Automatically filling? No, no. Those are definitely consumable items, and you brew them you drink them and they are very very important in terms of preparation before the fight.
(A bit more of a clarification here since I talked to another dev off camera. The potions/bomb system works like this: You get the recipe and it will cost a big amount of materials to craft, and you’ll get something like 3 charges of the swallow potion for example. When you run out, you will need materials to craft the potions again, but they will require only a fraction of the materials needed compared to when you first craft the bomb/potion.)
How is ingredient gathering for potions? Is it similar to how it was handled in previous games?
It’s very similar.
You can see the whole transcript here:
http://forums.cdprojektred.com/threads/31399-Kinley-goes-to-Gamescom
It's a recommended read.
However, there was another interview afterwards, somewhere in our main Interviews thread, that mentioned something different about the filling of ingredients. So at the moment there's no clear answer.
Also Geralt can now hold and release the effect of potions ?
then the timing of drinking potions is no longer relevant ?
If I understand correctly, there are two group of potions. Let's call them Major and Minor. The Major group are potions with significant bonuses that you can take only when outside combat, like in TW2. The Minor group are potions of smaller advantage that you can take during combat, like in TW1.
I remember some months ago that there was a lot of talk about "freezing" the potion effects and releasing them only when you needed it. I don't know if this element still exists, with this (I think new?) system of two groups of potions.
are there secondary elements like in TW1 ? (that was really cool) I also hope they haven't removed mutagens

((
Not sure.
Edit: Also,
@sandbox123 , skip to minute 27:00 in this video:
https://www.youtube.com/watch?v=xx8kQ4s5hCY
You can see Geralt meditating, and get a feel of how it's done in the game. If you pause the picture you can see that there's a slot for "Equipped bombs and potions", and a different slot for "Available mutagen potions". The potion found in the "Equipped bombs and potions" box is the same appearing in the quickbar outside meditation, so these are likely items you can use during combat, while the mutagens are more like TW2's system.