Supply, demand and consumer and producer surplus

Drug makers produce the generic for aspirin: acetylsalicylic acid. They sell it at lower prices than non-generic or so-called "brand-name" drugs, such as Bayer aspirin.

Does substituting brand name drugs (like Bayer aspirin) for generic drugs (like acetylsalicylic acid) increase or decrease consumer surplus?

Does the availability of generic aspirin increase or decrease the producer surplus for Bayer?

Does the availability of generic aspirin help aspirin production get closer to the efficient amount?