As a realistic painter, it's easy to me to answer your question, which is wholly understandable. Realism is one of the many visual languages you can choose to express yourself. Some of these are harder to paint and execute, yet some require more work on the concept. While with some other styles you can explore, for example, the materic properties of paint or abstract forms, speaking of realistic art, you can focus on exploring the dimension of subject or even depict things that cannot exist in a visual language that makes them read as "real". Also, if something looks like a photograph, it doesn't always mean the artist copied one, in fact you can also paint invented scenes and make them look as real. That said, what you see in my paintings is, for example, a highly idealised version of what I see in front of me which also many times includes elements that could not physically exist.

None in my case. Once you master the technique, last thing that interests you is sticking to that technique. There's no imagination involved, unless you're Rembrandt (he did cool things with light)