yes the npc vender is where the soup can be bought for 250 gold. Its a smart idea to leave a tame with a stash of gold at the freeport for future easy access to respecs. Id even suggest to the devs that the soup can be made at home by a master chef for easier access.
concerning the bug you mentioned. Back just a couple weeks ago when you used to be able to gain xp from beheading someone... befor SDC ruined it for everyone abused the hell out of it by placing alt characters in a corner of the powerstone caves as they farmed xp via farming the soldier of the damned, then beheading the alts for extra xp for their main characters.... when you beheaded someone, it would leave a deficit of xp but you would still have your lvl after bring beheaded... but as soon as youd repec after being beheaded, your true xp lvl would become your new lvl... now, perhaps although you can no longer gain xp by beheading someone, perhaps the person being beheaded can still lose their xp and their lvl goes to hell. honestly, i don't know as i haven't tested it since the update.