You could say their goods were for sale, but "as being" is accurate and used, though maybe not as commonly as "were". In this sentence, it almost implies their goods weren't actually for sale. They advertised their goods as being on sale, but in reality when we got there they had already sold out . . . or in reality they weren't accepting offers . . .

1. It is normal to follow prepositions with the --ing form of the verb. I don't see why you find this unusual. 2. No, there's no reduction here.

Could anyone help me?