Best Update Standalone Scenario

[Sivakatirswami]

I've searched through the email lists but it's huge and so I'll ask  
an old question (good candidate for an entry in the RevWiki Cookbooks  
section):

What is the best strategy to auto update standalones.

I'm finding some users are happier if every app we deploy is a  
standalone and then there are no issues about where the player is,  
opening the stack etc. especially where these apps have completely  
different job descriptions.

But then, if you want a standalone to update itself what do you do?   
Let me run this by you all for comment.

1) Keep a version number in a custom prop, in the stand alone.
2) have the app ping your server for a small file with the latest  
version number,
3) if they two don't match, then prompt the user to update.
4) on update, the standalone downloads a compressed version of itself  
to the folder that it is in and decompresses that file...
     Question: what is the best way to do this:
a) overwrite the previous standalone with the same name? Will all  
systems allow this if the file is open? I think not....
b) or give the standalone a new name the latter is pretty standard...  
"BBEdit 8.6, BBEdit 8.7"


5) then have the standalone save any open external stacks and quit  
itself.

6) now we leave it up to the user to
     a) reboot the standalone if it has the same name... (but, if  
replacing an open app is not an option, then this is also not an  
option.)
    b) trash the old version and boot the new one.

I would be interested in the overview, the options, the caveats  
etc... and of course cross platform issues (mainly OSX and Windows)  
for "best of show update strategies."

TIA
Sivakatirswami