Sanity check knowledge for custom ROM

[Guest andyrola]

I picked up an Moto G but haven't activated it.  I haven't yet decided
to install CyanogenMod yet, but I am researching the prospect.  The
reason is that it was bought from the ISP and so the OS isn't "pure".
I want an OS devoid of any ISPware for the peace of mind that nothing
will be monitored when I store confidential stuff on my phone (e.g.,
passwords, confidential info).  As a safety net, I would like to back
up the original ROM before any doing anything like rooting and
installing CyanogenMod.  I know that I can get apparent stock ROMs
from websites that are not the vendor's, but I would prefer to back up
the ROM on the phone, if possible.  I was warned that as a newbie to
smartphones, I would need to read extensively to ensure that I don't
brick my phone.

It has been a few weeks of evening reading, snippets at a time.  Weeks
ago, I followed a website (whose URL I did not record) in order to
install pieces of the Android Developer Kit.  I now have ADB and
fastboot executables on my Windows 7 PC.  Can anyone please do a
sanity check of the knowledge that I've "amassed"?

 * Root access is a concept that applies to a running OS on the phone,
   i.e., after execution of the ROM has commenced:
   http://forums.androidcentral.com/google-nexus-4/240307-does-flashing-stock-rom-remove-root-re-lock-bootloader.html

    - Hence, if you don't run the OS, you can manipulate ROMS without
      root, e.g., as in using fastboot

 * You need to unlock the bootloader to manipulate ROMS, which "wipes"
   your device as a security feature

    - According to
      https://motorola-global-portal.custhelp.com/app/standalone/bootloader/unlock-your-device-a,
      wiping will happen to all media, content, and apps from Google
      Play.  Does this mean that the OS itself is untouched?

    - Syntax found online: fastboot oem [un]lock

    - My fastboot's --help doesn't mention anything about the above
      oem command. I suspect that it because I specifically need the
      Motorola's fastboot (step 2 of FLASH AND RELOCK YOUR DEVICE at
      http://motorola-global-portal.custhelp.com/app/standalone/bootloader/recovery-images)
      rather than the Android fastboot.  My currently installed
      fastboot is at "C:\Program Files
      (x86)\Android\android-sdk\platform-tools\fastboot.exe".

    - Obtaining an unlock code from Motorola invalidates your
      warranty, even if you don't actually unlock the bootloader
      (http://motorola-global-portal-en-ca.custhelp.com/app/standalone/bootloader/unlock-your-device-b).
      Can anyone confirm this interpretation?

    - The unlocking of the bootloader -- where is the unlocked status
      stored and/or encoded?  I assume that it isn't encoded in the
      ROM that is being replaced, or the new incoming ROM?  Knowing
      where (or how) it is encoded lets would help me understand how
      the unlocking of the bootloader is retained if I should ever
      restore the original vendor ROM (apparently the unlocking is
      retained and must be manually re-locked with fastboot).

 * To back up the original ROM, one should use fastboot to run CWM
   without flashing (which I've seen referred to as soft-booting)

    - Syntax found online: fastboot boot CWMrecoveryImageFileName.img

    - I also found this syntax with"reboot" in place of "boot", but
      this is likely a typo because the reboot command doesn't take
      arguments

    - Also informative is that many fastboot commands require a
      partition specification, and the 4 partitions are (apparently)
      "boot, system, and if found, recovery, tos".

    - Backing up the stock ROM on the phone is not the
      end-all-and-be-all because, after some time has passed, the
      backed-up stock ROM is way out of date.

    - ADB will backup apps & data (depending on switches) but not the
      OS, so I conclude that it isn't the right tool for my purpose

Thanks for any comments on, or corrections of, my understanding.

Vetted info sites:

 * General CWM process for backing up original ROM:
   http://xiaomi.eu/community/threads/full-stock-rom-backup-without-rooting.22109

 * ADB backs up apps & data, depending on switches:
   http://android.stackexchange.com/questions/69567/what-all-does-adb-backup-and-how-do-i-restore-part-of-it