No, you will not be able to bring outside drinks, there will be drinks supplied for you. There will be wine, craft beer, and cider.
The dress code is semi-formal and/or cocktail attire. This means that tuxes and gowns are welcome, and so are suits, cocktail dresses, LBDs, dressy jumpsuits, and dark jackets and slacks.
Unfortunately, if you did not get a plus one on your invitation you cannot bring one, since the plates have already been accounted for.