Hi david king,
It depends on how you are exporting the file. If you are exporting the new job from Dev Local Repo to another New Dev Local repo. Which doesn't contain any data stores then you can import full job. It will create and rewrite the existing jobs.
If you want to export the job from DEV to SANDBOX. Where all the Datastores are available with its environment configuration. Then you can exclude the datastores configuration. irrespective it follows for all the objects in the job. If you imported the complete job then you might need change the System Configuration.
System Configuration:
There are some tweaks you can perform on the .ALT files to modify the Field names and data type size for the template fields through out the job level.
Regards,
Akhilesh Kiran.