ZE2/PHP5 API re: extension questions

I'm looking to update the libical extension I wrote awhile back to
use the new features of ZE2 in PHP5 (libical has been written in
such a manner that the features of ZE2 are an excellent match to
libical's interface). I've been looking over the
default exception class in Zend/zend_default_classess.c, and it
looks to be a good starting point for what I'd like to do.

So, the questions:

1. Using the __ function features (specifically I'm interested
   in __clone(), __construct(), __destruct(), and __toString())
   seems to just mean adding the appropriate entries to the
   zend_function_entry structure for the class. I notice that
   when the class is registered, the handlers.clone_obj entry
   is set to NULL. Am I safe in assuming that setting an entry
   to NULL in the handlers struct implies using the named
   function in the zend_function_entry list? (I think the above
   only applies to __clone(), __get(), and __set()?)

2. Private/protected internal class methods can be defined
   using the ZEND_ME macro with the flags set to ZEND_ACC_PRIVATE
   or ZEND_ACC_PROTECTED as appropriate? Also, static class methods
   can be defined also using ZEND_ME with ZEND_ACC_STATIC as the
   flags parameter?

   I guess I only have one class where an internal private/protected
   class method would be useful, but there are several classes that
   could benefit from static class methods.

3. Per-class constants: Almost every class in the libical extension
   can use per-class constants, but I don't see the code for that in
   the Zend API. Do I need to dig a bit deeper (pointers to appropriate
   Zend headers/files appreciated :) or is there a specific set of
   functions that doesn't have an API yet that I should be using?

Any help would be appreciated. Thanks!

-Bob