the Arduino IDE created bin is everything
Once I learned this, I saved lot of time in useless uploads and I managed to find my problem! The main problem was that I need to use DIO (or DOUT) instead of QIO. I assume this is due to a cheap Flash! In addition, I noticed a 10K resistor on GPIO0, in this last batch of ESPs I received is not enough to always enter Boot Mode. Replaced with a 3.3K seems working ok.
By the way, I discovered that, through "--flash_mode dio" modifier, the .bin can be modified during the upload phase.
I am not very convinced every ESP hobby developer knows the Espressif firmware is totally useless!
Thanks for your help - problem(s) solved.