Based on your description, please try recording your test as a user would interact with the page. Then run the test, and for any step that fails you can double click on the red 'X' for that step.
A failure resolution screen should then appear. If any of the page elements are not found with an error like 'Unable to locate recorded element', you can edit the find params on that screen as in this video
Please edit the find params to something that will be true for that created grid element at runtime using the find methods (TagIndex, AttributesOnly, XPath, Content). You can also use partial finds for the attributes and content to find the element you are looking for.
The new beta version uses an upgraded find expression scheme that can chain these find params together. So if the 2009.2 924 WebUI version is not working out for you, please try recording the test in the beta with its auto generated find expressions.
You can also edit the find expression in the beta similarly to the 2009.2 924 version, but with the options to add Atrributes from the pre-generated list or adding your own custom find expression. You can add a custom find expression by:
1) Double clicking into the first empty box and select from the list (TextContent, InnerList,...)
2) Select the drop down find method (Exact, Contains,...)
3) Select your custom find text
All the best,
the Telerik team
Quick Edit: About NUnit, here is a video
on code and Unit Test conversion from your WebAii test.