Can a work order be created via CSV import ?

No. However, you can import a supply plan then convert that to a WO if items are set to the Time Phased replenishment method. Other option is to create a custom record then have a script pick up the fields in the custom record and create the WO from there. This would enable CSV importing to the custom record.

There are some tools out there that enable importing of records that arent normally importable. I havent used any of them so cant personally recommend any