In Leads, I am customising Lead Source 

e.g. XYZ exhibition 2012 instead of cold call

can i copy amended lead source to have the same drop down list in contacts or do i need to create a new custom field from scratch called lead source and copy to potentials, contacts etc?

When i go to the next exhibition and meet leads or contacts will I be able to update the drop down and then use excel to import the new contacts/leads or will I have a problem?

I'd hate to add contacts now and then have to redo them all after the next fare.

Thank you in advance!

George