I think the other guys gave you good advice. I agree that you would have ended up with brownish mush in a slow cooker.
Freezing will work out great for you. I would, however, probably take the meat out of the marinade once thawed because 4 days would be a little long, esp. with the wine and the vinegar in the marinade. Keep in fridge after draining.
What to do for your guests?? Do you want to eat right when you come home (ie, everything has to be cooked and ready?)