Magento Import/Update of Products via WebServices

I want to get the following functionality developed by a highly skilled Magento developer: Objective: Update inventory levels from web service feed. A cron based import/update script that can call an external web service that requires credentials and delivers an XML feed of 3,000+ records with plus 5 nodes each. Upon succesfull retrival of the XML feed a scan has to be done through the records to determind which of the 3,000+ records needs to be updated in the Magento database - based on difference in inventory level. This could either be done through a record by record scan via the Magento API and subsequent update of the inventory level or through a match against an external MySQL table using SQL querying and subsequent updating in Magento through the API of only the selected records and final update of the external table. This is an example of the skill level I require from the developer - there has to be room/expectation of differences in approach to a development challange and a dialog to determind the best approach... Full documentation of the external web service is available here [login to view URL] And more work and deeper complexity is to be expected for the chosen development partner. I would require Skype access to the developer and above adequate level of English skills.