Arduino IDE - Need Clarification on OTA Firmware + SPIFFS partition

[TMSio73]

Hello,
inside my code, I have a web-server, the html code is inside the primary code (client.print (bla bla);).
When i update the firmware via OTA no problem.
I can update firmware and web-server.

Now, I would like to migrate the html code to an external file placed in the spiffs memory.
My question:
1 - Having the external html code, how can I update it in case of changes?

2 - There is a way to update both the firmware and the SPIFFS partition?

2 - Which is the easiest way to migrate the internal html code to an external file?

Thank you in advance.