If the WebGrid has been successfully deployed and display the page slowly, it is unlikely to be caused by the deployment method. Do you mind elaborating on the detail of the scenario? Is a large number of data is loaded? Did you enable all the WebGrid feature?

We already provided some article to improve WebGrid performance in our blog in the article; Rich Features in Low Client Footprint, Faster than “fastest ASP.NET Grid”, and Faster than “fastest ASP.NET Grid” – Part II

Testing the scenario using a simple test page on my environment does not reproduce the same issue. In my sample, the WebCombo result box will show without overlapping the content on the left. In order to achieve the result similar to your screenshot I have to use the AdjustResultBoxLeft property. Attached is the sample page I used to test the scenario.

Have you used the latest WebDesktop 3 and WebCombo 4, build 312 and build 220 respectively?

You need to create a new ChartPivotFilterConfig for ChartCategoryCollection with the date format of your choice. The default DateTime column month will display the label as 2010 - Q1 - Jan. The date format will accept common ASP .Net DateTime format. Here is a snippet:

<ChartCategoryCollection>
    <ISWebGrid:ChartPivotFilterConfig DataMember="OrderDate" DataType="System.DateTime"
        DateInterval="Months" DateFormat="yyyy-MMM" />
</ChartCategoryCollection>

Multiple column in UXComboBox could be achieved using template. You will need to modify both UXComboBox template and UXComboBoxItem template to show multiple column. My suggestion is to use Expression Blend to copy the original template in ItemContainerStyle and Style property and modify the original one. Attached is a simple UXComboBox with modified template to show multiple column.

The data is a collection of object with 3 property; ID, Desc, and Category. 

I have discussed this issue with the developer and he confirms that in the latest version client binding WebGrid has not supported WebDragDropExtender yet. The support is planned in the next major version of WebGrid.