More on this vampire feeding thing:
Feeding is considered an assault for about 200g bounty.
If you feed on an innocent person he/she will be stunned as usual but is also aggroed and acts like a normal enemy instead of running away or something.
I managed to run and hide, but you have to be really fast + guards attack you on sight.
I also noticed how incredibly useful the vampire speedsneaking is... I guess we have to brace for the impact of another vampire player wave.
EDIT: I forgot to mention that you are not able to talk to vendors, stablemasters and the like when you are a fugitive from the law. Annd... One of the guards in Ebonheart noticed me and screamed "Stop! You s'wit!" :D