Point 5 - not with this method. Application.OnTime will not work fine with second fractions.
As a matter of fact, I'd say excel is not best suited environment for such tasks.
The rest (but point 5) can be reasonably easily done, but does it make sense if you cannot achieve such critical part?

But to give you some hope - have a look on Zack Barresse code http://www.vbaexpress.com/kb/getarticle.php?kb_id=242