Hi Huno,
not terribly knowledgeable and speaking from T420-experience
I've read and used the blobs from the "damaged" custom BIOS. I'm not sure if this can affect the functionality of Coreboot. Apparently, it does not.
If you had damaged the ME firmware, you would not reach coreboot or any other firmware - the blob is signed If you had damaged the NIC firmware, ethernet would probably be broken, so that's clearly defined.
/(Let me know if anyone of you need details/help about/with the HW flashing in this type of chip (MX25L6406E/MX25L6408E)).
refining the wiki would be a good thing to do
*3.1) RAM speed:*
*=> So, if I'm understanding it correctly, current 667 Mhz is not the maximum ***speed *supported. Any idea on how I can get higher speeds?*
That's RAM _clock_ not data rate which is double the clock rate (-> DDR) - you're not any worse off than with the original firmware.