Supply, demand and consumer and producer surplus

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

1. Does the substitution of brand-name drugs (such as Bayer aspirin) for generic drugs (such as aspirin) increase or decrease consumer surplus?

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

3. Does the availability of generic aspirin help aspirin production approach the efficient amount?