Importance and satisfaction are only useful once you can put numbers against them, and you can do that without a research team.
Start one to one. Interviews are where you find out which questions are worth asking; surveys are how you scale those questions once you know them. Running it the other way round produces a large, confident, useless dataset.
Ask the two as separate questions about the same benefit. Importance sits comfortably on a five-point scale, from not at all important to extremely important. Satisfaction wants a seven-point one, from completely dissatisfied to completely satisfied, because the extra room lets people sit just off centre — which is where a lot of honest answers live.
Ask about satisfaction with what they do today, never with your idea. "How satisfied were you with how that went the last few times?" can be answered from memory. "How satisfied would you be if..." cannot.
Average the scores, or rescale them to 0-100 if that reads better. The precision is not the point. The gap between the two numbers is.