In some people with psoriasis interferon is contraindicated. It tends to make the psoriasis worse. I imagine that yours is moderate to severe since your doctor is prescribing enbrel. You need to talk to your doctors to get your answer to the questions. No one here knows your medical history. And yes, both meds can work for their respective diseases however interferon and enbrel work differently on the immune system and I don't know if they can even be taken together.
Could you be a bit clearer with your questions and you will get some replies.
Paul