We are also going to electronic storage for our termed employee files.  Things we considered were: 

Is the storage method reliable with back up ability?

What retention do you use?  We reviewed the individual documents that would be saved and the one that requires the longest retention is what we used for the entire file.

How will you search for your docs?  We use Nautilus so key words were very important.

What is the primary identification method for the document name?  With our storage software, we decided to make sure Employee ID number (everyone in our company has a unique number assigned to them for payroll purposes) was used for every single file.  Otherwise, there were too many variables that we could encounter when they were inputted.  For instance, if you used a name like McCoy...some people would enter it as Mccoy, some as Mc Coy some as Mc coy....you can see the number of variables.  Because of the variances that were possible, we decided to stick to something that was unique to head off these issues.

How long will you keep the paper to back up the electronic? 

What will be your quality check to ensure that the entire file was scanned?  and scanned correctly and the images are clear enough that they can be re-printed if needed for an audit?

Who will have access to the images? from the manager to the IT personnel that manages the software program.

How will you manage the docs that have to be separate from an employee file-like those guided by HIPAA?

What retention schedule will you follow?

Do you have clear procedures and policies regarding both how to image the docs as well as  how to access-both for third parties (auditors), direct supervisors those above?

How does your storage handle the countdown for retention?  We input a term date field-if nothing is entered there, the document stays indefinitely.  Once we input a term date, the retention clock starts the countdown so that it automatically dumps the file once it hits it's retention date.

The above is what I remembered off the top of my head-I'm sure there were more but at least this gets you started.