I decided to root the Mrs Kindle Fire 1st gen, all good so far! I was able to root it, add TWRP, FFF a ROM and gapps.
however, my question is: Can I copy files to it by connecting it to a PC? Before with the stock OS, it would show up on windows explorer and could copy/paste files to it. Now, even though it does load the driver and appears as "Android ADB interface", does not map a letter to it.
Not worry much, since I can use "ES file explorer" for network shares, but would be nice for big files.