Can I do "multithreaded" apps for Acad in VBA?

That may not be the proper term, but heres the gist of it.
I have an application which I load through the startup suite, it is then
initialized via SS:startup in AcadDoc.lsp
this initialization merely sets some global variables such as the document
name etc. it then calls the main program
which checks numerous conditions in the drawing. This initialization, being
in the ss:startup, is run each time a drawing is opened.
That last sentence there is the crux of my dilema. I want this program to
initialize and run each time a drawing is opened, including
when multiple drawings are open.
At this point, Im not sure about the proper use of the AcadApp object and
AcadDoc object. Should I create global references to them
at the start of the program so that any "peripheral" fuctions I may invoke
(either during or after the main program has run) will have acces
to these global references, this also seems to imply that at the end of the
main program these refernces are NOT set to nothing since other
functions will need them later (thus depending on VBA to "garbage clean" on
end of acad).
Or should I clear these references at the end of the main program and any
other functions that may need these will declare, then clear,
their own copies??
After trying the first method, using global references, I thought this may
be wrong. Since after closing a second document, the first document
seemed to "lose" the value of AcadObject and AcadDoc.

I am also kinda murky on the use of Events within this program. I am using
the ss:startup mentioned above because the "BeginOpen" event
isnt quite right for this app because it fires before the drawing is fully
opened so I could get some weird results. The BeginOpen event also
does not seem to fire when Acad is first invoked. The "NewDrawing" event
also doesnt seem to fire when Acad is first invoked. Alternatively
the "BeginClose" event seems unfit for what I want because like the
previous, it fires before the drawing is fully closed (and any underlying
document,
if any, gets the focus). So for example if I want to re-establish the
current drawing name during this event I get the wrong name.
So I have got into the habit of extensive use of the "EndCommand" event and
doing things there. My main question then is since I want this
application to run its own independent copy for each open drawing, should I
check for events indicating a drawing has closed and set the
AcadObject and AcadDoc references to nothing? (assuming Im using the
"global" method) Also, in this same vein, should I check for the
DocActivate and Deactive events and do the same (including setting New
Object references)?
One more thing on events. I have put all these in an EventClassModule and
there are a few lines in my initialization code (which runs on each
open drawing) which initializes these event functions. Is it proper to
initialize these events on each drawing, or should it be done only once
during an Acad session?

Theres quite a bit of good vba example code out there, but I havent yet
found any that makes extensive use of events, or any that
is clearly designed to run in muliple instances. The documenttation is kinda
skimpy here too. Anyone know where I might find
some of this treasure?
Thanks for any tips.