node access relations and user field privacy.

I suppose that depends on what you intend to do. They each have different use cases. I'm not aware of any specific incompatibilities if that is what you are asking, but no effort has been made to integrate the functionality of these modules either. If you can narrow the scope of your question I might be able to provide a more useful answer.

It should be possible to do what you want, but I would recommend something like the User Relationships module to manage the relationships between users (friend, coworker, enemy, etc). I'm not sure how useful the other modules node access relation and user field privacy would be in the case you describe. Most of the other privacy type modules out there are geared toward making something either public or private. The goal of this module is to allow for arbitrary levels of privacy (public, private, only friends, only on tuesdays, etc) and allow each user to set their privacy level for the predefined types configured by the site builder. So for your example you would create privacy types for each field (hobbies, jobs) and enable the profile privacypu submodule to allow the user to set their entire profile as private. Then add checks using privacypu_check_access() in a template preprocess any time you would normally display those fields. Then it would be up to each user to decide and select the types of user relationships they want to allow to see their stuff for each of those types. This is all about user choice, so if you are trying to create a hard coded set of privacy rules that apply to everyone then this isn't a good solution for you. In that case I might just use User Relationships with some custom code in the template to check whether each field should be displayed.