Hello Avi,
K2 templates can be completely overridden so no need to hack anything.
1) Yes, K2 supports both extrafields and front-end editing, also the front end editing form can be overridden as well.
2) Yes, K2 offers extended ACL and multiple K2 User Groups with different permissions each.
3) This can be done with a simple JS script in the the front end editing form
4) Custom fields can be individually rendered at any part of the K2 template. You can perform a simple PHP check and according to the field's value, show the appropriate code or file (using a PHP include).
Hope that answers your questions.
JoomlaWorks Support Team
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