New Post: Update only modified properties

Thanks for the code, it really helps as there are so many different ways of implementing this out there.
I've used this code to implement unit of work with EF5, with certain modifications. Can you throw some advice on how to:

1. Is it possible to make a change so that only modified fields are updated. I've seen that it works fine when you are working on a single context, but not when you set EntityState and Attach the object. Is iterating through the properties one by one, my only choice?
   
2. If I need to implement auditing of changed fields (with each table having a corresponding History table with nullable fields), what is a good way, other than, again, iterating through all properties and Inserting an additional History object?
   

Thanks!