What types of work are done in a typical Research & Development department?

Janitorial. Never anything else.

Just guessing, in general-
Research use history of product (complaints, returns, etc) to determine areas of possible improvements.
Devise methods of testing products.
Record data obtained from testing.
Determine if problem areas should be addressed by better materials and/or better manufacturing techniques.
Analyze cost of improvements.
Research need and cost effectiveness of developing and introducing new products to the market.

ok thanks

No, I am pretty sure tsar nailed this one.