polymorphic question w/r/t acts_as_taggable plugin use

I've been using the acts_as_taggable_on_steroids plugin successfully for awhile with models descended directly from ActiveRecord, but just ran into something strange in a new use case where I have models that are subclasses of other models.

I'm looking for an explanation and a workaround or correction to the way I'm doing things and it occurs to me that someone may have an answer if they have good knowledge about rails' polymorphic operation OR about the way acts_as_taggable works...

Here's my problem -

1) Models -

class Group < ActiveRecord::Base

class Circle < Group

class SupportCircle < Circle

2) I have Circle declared as acts_as_taggable

3) when I tag a Circle, the 'taggings' table record for it has 'Group' for the 'taggable_type' column

Q1: why isn't it 'Circle' for the 'taggable_type'? Q2: where in the code is this assignment of the value done? (I can't seem to find it and assume it's some "under the covers" magic that Rails is doing...?)

4) acts_as_taggable.rb's 'find_tagged_with' method does the query with a join that has this fragment:

AND #{table_name}_taggings.taggable_type = '#{name}'

So, when I do a search for Circle objs tagged with a tag, it fails to find those tagged objs because when I call Circle.find_tagged_with(tag), the 'name' is coming in as 'Circle' while the entry in the table is 'Group' as described above.

Q3: why is the search value inconsistent with the 'tagging' insert's assignment of value for 'taggable_type'?

5) I want to start tagging SupportCircle's and not sure of a few things...

Q4: with an acts_as_ declaration, do I need to explicitly declare that in a subclass or will SupportCircle be taggable because Circle is declared so? Q5: if I want to distinguish between Circles and SupportCircles in my searches, I do separate calls for each with Circle.find_tagged_with(tag) and SupportCircle.find_tagged_with(tag) respectively, and from the look of that query, I'll *only* get Circles from the first and SupportCircles from the second, right? (yes, I think... just checking 'cause of the unexpected behaviors I'm seeing)