Return of Reckoning

So, where is this npc? i took the quest Encroaching Darkness, and made burning windmill quest, and now i have to go give the quest to the npc, but hes not on a marker/map. Halp?

Hi, so im making the emperor mandate quest and cant seem to find Lieutenant Wilhelm, i mean i spoke to him before but took some quests and forgot where he is:d anyidea where can i find him?

So, its my first post as i started RoR today, and never played Warhammer. I cant find Sergeant Arnoldt from the quest The End is Nigh. is this quest essential? can i abbandon it without big problems? Or maybe someone could point me in his direction? As hes not on map and dont see him anywhere?