Some suggestions, commonality due to mailing, payment details and the like set up seller details and use a template.
If you have thousands of discrete items then they will all need sperate photographs and descriptions anyway. Big job, photograph with numeric lot numbers and upload the images in bulk on to Auctiva and store in folders representing batches to keep it manageable.
Then create the listings and for batches of similar items use 'create similar' option to reduce typing fatigue, it all helps. Good luck