I was hoping some of you would comment on how many CFM was enough for a vent hood. For a new construction, I am looking at wall mounted vent hoods for use over a 30" induction cooktop. I've only used recirculation type under-cabinet hoods before and have found them to be basically useless (except for the lights). I know with higher CFM there is also increased noise and cost, so I'd like to ask if anyone had thoughts as to how much is enough.

Secondly, intuitively I would guess that electric/induction cooktops need less ventilation than gas. Has anyone noted a difference?

Lastly, I'm planning to place a single oven under the cooktop, primarily so that the vent hood can filter any undesired odors from the oven. Since I've only used cheap ventilation over a range before, it's never really helped. Will a good hood actually help filter the air from an oven mishap? Otherwise I'll place the oven somewhere at eye level (easier on the back).