You seem to go more broadly than topic
Back to the yafimsky question:
Barry has right. It's hard to get started on GS API. However it's not impossible. I had several attpemts based on documentation and white paper. Recently I have found API Blog which solves all beginners mysteries. For the beginning I suggest two crucial posts by Akos and Tibor:
Here you will solve MDID mistery:
http://archicadapi.graphisoft.com/hello ... and-button
Here you will solve VS2017 compiling issue:
http://archicadapi.graphisoft.com/worki ... tudio-2017
And helo word(this one didn't work for me but probably it was vs2017 problem)
After those 3 post, you should be able to compile examples form API.
Please keep up with those blogs written as a coherent tutorial with each step described it way easier to understand than learning from docs.
Back to the cloud point what kind of file format are you trying to use?