Espruino on ESP8266

(I am not that skilled on using Git and Github and am looking for community assistance ... beneath are notes on my current thinking as well as the questions I have ... )

Let us review the Github environment used to build this project. There are a number of players in this story. The first, and arguably most important is espruino/Espruino. This is the home project of Espruino itself. The ultimate goal of the ESP8266 project is to create changes and new code and have that published in espruino/Espruino. At that time, there would be no further need for any other projects.

However, during this development period, we need a second project that will be used to host the ESP8266 work that is in flight. Currently, this is a stand-alone Github project called esp8266-espruino/esp8266-espurino. By stand alone, we mean that this is a file by file copy of the espruino/Espruino project with changes made for the ESP8266.
Unfortunately, this does not feel right either.
What we need to understand is the following.

Let us assume that we can fork the espruino/Espruino project under the "esp8266-espruino" organization.

(See the attachment)

We will now end up with a project called "esp8266-espruino/Espruino" that is modifiable but will not contaminate "espruino/Espruino". When ready, a pull request can be submitted to "espruino/Espruino" where the owner can then merge in the changes made to "esp8266-espruino/Espruino".

Question:
Is this an all or nothing story? If many changes are made to the "esp8266-espruino/Espruino" project and only a "few" files are to be incrementally submitted into "espruino/Espruino" ... can this be done?

Question:
Can changes made to "espruino/Espruino" after the fork be pushed (pulled?) into the "esp8266-espruino/Espruino" project?

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