The short answers to your questions are YES, YES, and YES.
But you need to be very aware and clear of the long answers. While the FMCSA rules and regulations do not apply to van drivers (unless your van is, at the time, a CMV, meaning placarded for HAZMAT), many of the carrier's policies mirror that of the FMCSA rules and regulations just the same.
You can consume alcohol out on the road, as long as you are off-duty (out of service). If you have a Friday pickup for Monday delivery, for example, and have pretty much the entire weekend to kill while waiting to deliver, you are on-duty and in service and thus cannot consume alcohol while loaded.
You cannot use alcohol, or be
under the influence of alcohol, within 4 hours before going on duty or operating, or having physical control of, a commercial motor vehicle. In addition, while in-service you cannot use alcohol, or be under the influence of alcohol,
or have any measured alcohol concentration or detected presence of alcohol. So, at least 4 hours prior to going back in-service, you need to be stone-cold sober, and by the time you actually go in-service, your blood alcohol content must be essentially zero (.04 percent).
With very few exceptions, you cannot consume alcohol while inside the van, as most states have open container laws which prohibit an open container of alcohol in any public place, including inside a vehicle. See
United States open container laws for the open container laws and exceptions.
Once in-service, you cannot have any beer, wine or liquor inside the vehicle at all, even if you don't intend to drink it until three days from now.
Read this thread:
http://www.expeditersonline.com/forum/general-expediter-forum/34143-mouth-wash.html
Basically, unless you are out-of-service, with most carriers you are subject to be called for a random drug test at any time day or night, and you can bet dollars to donuts that if you're drinking out here, that's precisely when the phone call will come.
