Are all the forged items better than one's you buy normally (this is the first chapter i'm talking about)? For example. You can forge some armor (can't remember the name... Charamtic breasplate possibly..) is the Full plate mail (the strongest you can buy in chapter one) more powerful?

I only talk about weapons: Yeah weaponsa are all better forged then found at least in chapter 1. Later in chapter2 you already find better items if you are lucky :)

The Whitebone Armor +2 is the best IIRC. It has a total +9 to ac. And it looks quite cool...

My current armor gives a total +10 to AC, and there are even better ones out there.

Yeah you may have an armor with 10AC but you certanly arent in chapter 1. ;)
Whitebone can be forged quite quickly in the game as soon as you get some money to buy the armor(IIRC twenty in a quiver) and know the location of gargoly skull. :)