Magento XML Order Import Integration Bug Fixing

I am importing sales order data from 3rd party sales platforms via XML thru magento API - things were going ok but now have some bugs that need fixing! I need someone very experienced with magento API who can identify and fix these issues fast and painlessly. 1. Orders from one platform have stopped being imported since few days - need to fix this and backdate all orders to 5 feb to retrieve all missing 2. It is not possible to mark orders from one source as shipped once invoice has been created in magento - get long mag error message if you try 3. One order platform has orders imported with incorrect quantity (imports 3 times for each product purchased) 4. Admin grid functionality is diminished - cannot select mass products and action commands in admin (using Fooman) - example : cannot select multiple orders and batch print invoices; only first of selected range opens to print. Please contact me if you have read this and can fix it up correctly and quickly THANK YOU