"I have four (4) 3rd party smart outlets from different foreign (china) vendors that were easily supported under Alexa and would like to have them supported under Google. They are used to turn on lights, fans and electrical devices."
You would need to check the manufacturer to ensure they support Google. Documentation may say "Works with Google" or "Works with Google Home" or "Works with Hey Google".
"Would also like to add some remote wireless cameras and a video doorbell to the Google system. I would like for the doorbell and cameras to be displayed on my PC and Android phone, not necessarily simultaneously, and still have them controlled by the Google system or Home App, if possible. If I need to purchase a Google device to display the Cameras and Doorbell video, I would like to know what is needed."
Up until recently you could only control Google Home by voice from a speaker, a hub display or from a mobile device with the Google Home app installed. Recently Google released a web interface that works via browser. So you can view video on your phone, via a browser, on a hub display, and on some TVs.
"Does Google use their device heavily for marketing, pestering you to get you to use an App or to constantly inform you of new features or functions whenever you interact with the device?"
That's a bit subjective, but in my opinion, no.
"Can I simply use the Android Home App on my phone and the phone's display to control and display everything, including the Cameras I want to purchase, or do I just need the Home App and a NEST Hub for this? "
The Nest Hub is not required. You can control Google Nest products using Google Home. There are some limitations on the older Nest products in which case you may need the Nest App as well.
