Maybe there is a missunderstanding among us.
1- PRO does not offer the Demos like X. so for example Integrity 1, Renew 5, Gym or App Demo and all the others are available just on X not on PRO. There will be soon a new functionlity released for PRO which will cover this, we are almost ready with that, but we cannot provide an ETA for the release.
2-To access the page builder (it is very similar to Cornerstone at this stage, but we don't call it Cornerstone as the future will bring changes ) and as well where you can find your templates which I was refering are on Pro > Launch > Content > Select a page > Edit
3- Here is the link to our Knowledge base : https://theme.co/apex/forum/t/knowledge-base-overview/287
I do agree it can be improved, we had a meeting a few minutes ago and we discussed about it, so expect some improvment from our side regarding the documentation.
Let us know if you have further questions