For views, I recommend pushing all your views into a hook_views_default_views function (just export all the views).

You will also need to clear the views cache whenever a change is made to this file (writing _update_N function for this if necessary).

For _ANY_ php you use in _any_ block/field defaults / etc whatsoever, i recommend creating a function in your support module and calling this.
Life is too short to not have all code in revision control.

I am really looking forward to cck 2 , as it will also implement the default_types and default_fields hooks, similarly to how views does it.