[color:"orange"]1. What are the best categories in the 2 handed skill to put points in?[/color]

Damage and Accuracy. Don't neglect Sharpen Weapon, though! It adds a lot more damage to weapons, though it adds an Agility requirement too.

[color:"orange"]2. Potions besides the red, blue and white, are the others worth keeping? Do you really need a constitution potion or stamina potion etc.?[/color]

I'm holding mine for a tough boss.

[color:"orange"]4. Are the battlefield dungeons extremely borring, or is it me?[/color]

They're boring. I don't mind a mindless hack-fest once in a while, though.