Translation:It is a furniture store, food is not sold here.
In other news: "A worker standing in a liquor line says, 'I have had enough, save my place, I am going to shoot Gorbachev.' Two hours later he returns to claim his place in line. His friend asks, 'Did you get him?' 'No, the line there was even longer than the line here.'" https://www.cia.gov/library/readingroom/docs/CIA-RDP89G00720R000800040003-6.pdf
Not always, no. This is an extremely tricky part of Russian. Genitive is always used with negation in instances of existence: "У нас нет еды" (literally: At/by us, [there is] no food).
With transitive verbs, the general rule is that negation with the genitive is preferred for intangible things: "Я не помню твоего адреса" (I don't remember your address), and the accusative is preferred for tangible things: "Я не купил ету книгу" (I didn't buy this book). Using either grammatical case in either situational case isnt WRONG, necessarily, but it may sound unnatural. Regardless, you'll be understood either way. "Я не помню твой адрес" will he perfectly understood by native Russians.