In particular, if someone makes it through to the end of your landing page, you have a final opportunity to convince them to convert (incidentally, this is a good place for another CTA). With your closing argument/reinforcing statement, you should summarize everything you covered in the rest of your landing page and then throw in any additional selling points you think might seal the deal.
Prospecting and marketing are all the things you do to get people into the first of your sales funnel stages. Note that stages are broken into two or more steps wherever possible. A demo could be called a single stage, but in real life it involves a lot of things: contacting the customer, sending reminders, doing the demo, and then following up. Whatever your own sales stages look like, the support you need in managing them will be the same.