[Sparkle] Sparkle Integration Questions - Customized Applications

[Dean Shavit]

Hello,

my application is customized by its end users in several ways, so my  
challenge is to make Sparkle preserve that during the update process  
while still using a single appcast source

So, I have a few questions

1) is there some sort of "pre-update" action that can be scripted to  
move certain plists or pictures from inside the app bundle prior to  
the update to /tmp then back into the app bundle after the update  
with a similar "post-update" action?

2) are there Cocoa notifications that can be sent from the framework  
to my app to trigger pre and post-update events?

3) has anyone has any success appcasting a .pkg file with pre and  
postflight scripts?

4) is there a way to preserve the application name and a custom icon  
during the update process?

TIA

Dean Shavit