I have already gone through the link before posting the message here. My question is:
Once the site has been added to Cloud Flare will it automatically start pulling the content off our server and start storing the same into its cache or does it cache the page only when it has been requested by the user?
The user will need to request the resource, and the response will need to satisfy the conditions for the server to cache it (i.e. appropriate cache headers, no Set-Cookie headers).
You can see the cache utilization % in the dashboard. Once Cloudflare starts serving your content, this % will increase.
Cloudflare won’t cache the new resource until someone visits your website after the previous resource has expired. It doesn’t actively scrape your origin.