Journey

Finally, I played the latest beta version over the weekend. The map is just awesome! I started playing as a Paladin, but I started losing, so I switched to Constantine, a Necromancer, and things started going better. I almost forgot - the portal next to the brown Orc and the tree of sight is not working; maybe it's intentional, but all the other portals work except for that one. I'm a little confused about the quests. If I choose one, and then complete it, will I be able to choose another? And if, for example, I destroy the Orc castle, but I didn't take the quest for it (although I think there was one), will I be able to complete it later? I'm playing on easy mode, which is not typical for me.