If you have made any changes to template files itself - they will be lost after update so you would need to merge them manually. All data like articles, modules settings etc will stay intact.
but have an Problem with the grid gk 5 also ... there are 8 entrys in K2 who links to grid... but there are double entrys .. you can see here http://joergschnitzer.de/web/ last 3 entrys - 3 times the same .. also the pictures from are not correct .. changes are not provided !
Please read how grid actually works: http://www.gavick.com/documentation/joo ... k5-module/ Now on your site grid loads modules published in grid1 position - and those are NSP modules. Each is set to a specific source and that might be the problem of the configuration. Please check if NSP modules are configured correctly.