Ideally you separate the two questions into two posts, because they are completely non releated from what I can see:
2. Not possible out of the box. You might be able to use a second question with ony "don't know" and then format it accordingly so it looks like one question.
1. I think what you mean is that you want to screen out certain participants that do not fit the profile of the survey. To do this, you can use quotas. In this specific case you need to use so called "zero quotas", so the value of the quota is "0". This means that everyone that fits in the quota will be seeing a end message that you define in the quota and can also be redirected to a specific url if you want.
2. Not possible out of the box. You might be able to use a second question with ony "don't know" and then format it accordingly so it looks like one question.
1. I think what you mean is that you want to screen out certain participants that do not fit the profile of the survey. To do this, you can use quotas. In this specific case you need to use so called "zero quotas", so the value of the quota is "0". This means that everyone that fits in the quota will be seeing a end message that you define in the quota and can also be redirected to a specific url if you want.