How do restaurants/businesses get their beer? Do they get them from stores, or do they set up a distributor? Also, is it cheaper than getting the beer from a store?
Some businesses (brew pubs and brewery taps for example) produce their own so don't have to buy it. Most businesses (pubs, bars, restuarants etc.) order from a wholesaler or cash-and-carry in the same way that they order pretty much everything else, or they may order direct from the brewery or an distributors. The prices are wholesale price so cheaper than they would be in a store so that they make a profit.
I help to run a beer festival in the UK and we tend to order our beers from distributors or direct from the brewery (we know most of the 50+ breweries in London well enough that a few donate some barrels as well as we are a not for profit organization). A distributor works partially as a broker between breweries and buyers and partially as a wholesaler, the difference is that they tend to keep the beer at the brewery and only pick it up and transport it to fulfill an order. One of the distributors that we use is FlyingFirkin http://www.flyingfirkin.co.uk/ , just to give you some idea of how it works.
Additionally, in the UK, duty is paid at point of sale so VAT is paid on the beer when it is bought from the supplier but duty is only applied when it is sold to the end user, or "drinker", and so the price paid from the supplier will be significantly lower.