Hi Kristy,
The only way to check if a segment you created is matching the right visitors will be to act like the visitors you want to match (i.e visit the relevant pages/ use the specific search terms or referrals defined in your segment).
If you use location, firmografic or known lead data in your segment, I'd recommend letting the segment run a few days before launching the campaign.
This way you can analyze the visitors that matched it by clicking the ### Distinct Visitors on the segments page and verify they were all indeed qualified for your segment.
Regarding your second question, you can use the campaign target URL to define specific pages or URL patterns where your campaign should be displayed on. Here is some more information:
https://docs.marketo.com/display/public/DOCS/Adding+a+Target+URL+to+a+CampaignLet me know if you have any further questions.
Yanir.