LENSOVET  Yeah, I'm aware of this, it's due to memory handling (mostly) and was introduced as part of my attempt to remove the previous memory leak. I will be resolving this in the next release.  
(Version 2.1)

LENSOVET  Yeah, those are API issues, and I already check for them on all methods – except for the photo comments one. This will be fixed in the next version, I'm just waiting on how to resolve some memory issues with Apple's Cocoa methods.  
(Version 2.0)

LENSOVET  Facebook's API had some troubles last night. It should work normally now though. Sorry for the inconvenience.  
(Version 2.0)

LENSOVET  Unfortunately, photo comment count will actually be dropped from the next release because Facebook dropped the feature from the API. If you don't like that, let them know (there's a link on the program webpage)!

Keychain support is something I want to do in the next release, if it's possible. Unfortunately, the only "cookie" that I'd have access to will be from Safari – I don't see being able to use cookies from other browsers as being anything close to manageable.  
(Version 1.7)

LENSOVET  As Lpod correctly pointed out, all the pop-up notifications can be changed and turned off in the Growl prefpane – just click on the Applications tab, then choose FMenu from the top list, and uncheck the notifications you don't want to receive.

Since the app is designed to give updates near-instantly, they are broken up to prevent facebook from blocking your account. If you want more rare updates, just set the interval in the prefs to some really high number (i.e. 6000 seconds) and use the "Force update now" menu item to refresh the data.  
(Version 1.7)

LENSOVET  Thanks! Unfortunately, as mentioned on the program's homepage, if your friend isn't showing up, that means that they have not released their info to the Facebook API.

Tell your friend to go to http://www.facebook.com/privacy.php?view=everyone and make sure that the box labeled "My information may be used according to the restricted Terms of Service" is checked.  
(Version 1.6)