I wonder if someone knows any C# script that will provide me all Site Features in a site collection as well as all Site collection features in a site collection.
I only required Activated features (GUID).
I think that when you use the Feature property in a SPSite or SpWeb you only get the active features on the "site collection"/site. So the code under will give you the active features on a site collection and all the sites in that site collection (write it to a file so you do not miss any because of the cmd buffer).
This should get you started : http://www.c-sharpcorner.com/blogs/7698/get-the-list-of-activated-features-in-the-site-collection-an.aspx
However, it only shows the guid and not the feature name.
Alternatively you use these scripts:-
Features are activated for an SPSite:
List all activated web scoped features