I work for an Apple Sollution Expert that specialise in Education.
With regards to upgrading OSX if you purchased any Mac or an OSX Volume license after a new version has been announce by Apple (ie 23rd June this year Snow Leopard was announced) you qualify for the free upgrade refered to above. However this will now not be the case until 10.7 is announce. Apple therefore offer a discounted upgrade price for anyone upgrading from the previous version (currently 10.5 to 10.6). We are currently supplying these to educational establishments for £18.50 per license.
If you have any further questions about Apple Macs / Apple Licensing i would be more than happy to answer them to ensure you have all the correct information for your possible project.
