As a professional services firm we need to capture any relationship that a "new hire"/staff member has with our existing Contacts/Accounts.  

To be useful I need these users to specify the extent of this relationship (via a custom field I have created) and record the date that they made this entry.  Once updated all fields should be locked to prevent future edits.  

Assuming someone can resolve the need to have a LookUp field that lists our users/staff members I am assuming the only means for handling is to create a Custom Section within Contacts with fields like Emp1, Emp2, Emp3, Emp4, etc .and HOPE we don't end up having any individual Contact who is known by more than the number of these fields I create????

Is that accurate?

Lastly, since most senior staff members will likely "know" hundreds of Contacts doing this one record at a time is highly inefficient.  To this end I assume the only solution is to create a "Search" that grabs a bunch of these Contacts and then go to a table (? maybe wrong term) view where it is dumped into Sheets and can be modified and re-uploaded?