Kitchen extractor point

Hi I wonder if anyone can help or point me in the right direction. I want to add an induction hob on a kitchen island and I have an open plan kitchen as well and I understand that an extractor fan would be good as it will get rid of smells etc... the questions that I have are
1. Is a downdraft extractor any good so that way I can put the ducted installation through the floor board before I add my new laminate and then directly outside length will be approx 2 metres from kitchen island to...

Kitchen extractor point