Can MHonArc find threads of deleted parents?

[East Coast Coder <eastcoastcoder@xxxxxxxxx>]

I'm a bit concerned about the performance issues of having MHonArc
scan the entire mbox for each update (I'd like updates every few
minutes), as well as the storage issues of having to keep the entire
mbox (as well as the html).  So, I'd like to delete the messages after
MHonArc processes them.

1) If I do delete old messages from the mbox, can MHonArc still track
the threads?
2) Am I the only one concerned about performance here?  It seems to me
crazy to have to scan a year's worth of archives to do each update. 
Am I missing something?  What type of load is MHonArc using?
3) Does MHonArc have any ability to delete the message from the mbox
when it's done?  (If not, I guess I'd have to set up a cron job to
delete old messages every night...)

-ECC