On Wed, 3 Aug 2016 03:18:12 +0000 (UTC), Aardvarks wrote:

a. Does not having a Google Play account eliminate the Advertising ID?

Facts only.

It seems Apple iOS devices have a resettable Identifier for Advertisers
(IDFA), which can be rest on iOS devices using:
Settings-Privacy-Advertising-Reset Advertising Identifier.

So, in that sense, iOS and Google seems to be similar; although it appears
that the Google Advertising ID "may" be easily removable on non-rooted
devices simply by deleting your Google Play account (still working on that
premise).

Apple iOS devices also have a Unique Device Identifier (UDID).