Hi Kilty,
Toilets in hotels/apartments are generally of Western standard - others can vary in quality and publicly available ones or those in bars restaurants, etc., will amost inevitably cost a few Stotinki for use (around 20-50 Stotinki usually).
There are lots of
local beers, but Kamenitza & Zagorka are probably the biggest sellers - they are typical lager beers and are pretty good.
Bartering is not expected in Bulgaria - a street trader in the resorts may be able offer a slight discount if you are buying more than 1 of a particular item.
Baldur