it depends - if you're starting from bibtex, the first question is if the field is imported into Zotero.
If it is, most, but not all, fields _can_ be used in a citation style - but I don't think any current style does. You'd have to modify one to do what you want.
Specifically, attached notes cannot be cited in a bibliography at this time. The content of the extra field can (<text variable="note"/>)

yes, extra isn't printed by most styles (I'm not sure if there is even one in the repository that does). It' easy to do, though, by adding
<text variable="note"/>
in the bibliography section of the style
http://www.zotero.org/support/csl_simple_edits
for general instructions.

The citation style element 'bibliography' looks as below. Please advise where the element <text variable="note"/> should go. In seems that there are many insertions of this element already. Is the attribute 'variable=note"' supposed to be added to each text element within 'bibliography' element?

<bibliography>
<option name="hanging-indent" value="true"/>
<option name="et-al-min" value="4"/>
<option name="et-al-use-first" value="1"/>
<sort>
<key macro="author"/>
<key variable="title"/>
</sort>
<layout>
<text macro="author" suffix=","/>
<date variable="issued" prefix=" " suffix=".">
<date-part name="year"/>
</date>
<choose>
<if type="book">
<group prefix=" " delimiter="" suffix=",">
<text macro="title" />
<text macro="edition"/>
<text macro="editor"/>
</group>
<text prefix=" " suffix="." macro="publisher"/>
</if>
<else-if type="chapter">
<text macro="title" prefix=" " suffix="."/>
<group class="container" prefix=" " delimiter="">
<text term="in" text-case="capitalize-first"/>
<text macro="editor"/>
<text variable="container-title" font-style="italic" suffix="."/>
<text variable="collection-title" suffix="."/>
<text variable="event" suffix="."/>
<group suffix="." delimiter=", ">
<text macro="publisher" prefix=" "/>
<text macro="pages" />
</group>
</group>
</else-if>
<else-if type="thesis">
<group prefix=" " suffix="." delimiter=". ">
<text macro="title"/>
<text variable="genre"/>
<text macro="publisher"/>
</group>
</else-if>
<else>
<group suffix=".">
<text macro="title" prefix=" "/>
<text macro="editor" prefix=" "/>
</group>
<group class="container" prefix=" " suffix=".">
<text variable="container-title" font-style="italic"/>
<group prefix=", ">
<text variable="volume" />
<text variable="issue" prefix="(" suffix=")"/>
</group>
<group prefix=", ">
<label variable="locator" suffix="." form="short"/>
<text variable="page"/>
</group>
</group>
</else>
</choose>
<text prefix=" " macro="access" suffix="."/>
</layout>
</bibliography>