Sure, I can help you with that! In Excel 2007, you can change the legend scale of a surface chart by following these steps:

1. Click on the surface chart to select it.
2. Click on the "Chart Tools" tab in the ribbon.
3. Click on the "Format" tab within the "Chart Tools" tab.
4. In the "Current Selection" group, click on the "Chart Elements" dropdown menu and select "Legend".
5. Right-click on the legend and select "Format Legend".
6. In the "Format Legend" dialog box, click on the "Number" tab.
7. In the "Category" list, select "Scale".
8. In the "Minimum", "Maximum", and "Major unit" boxes, enter the values you want to use for the legend scale.
9. Click "OK" to apply the changes.

To increase the number of contours in the plot, you can adjust the settings for the chart's data series. Here's how:

1. Click on the surface chart to select it.
2. Click on the "Chart Tools" tab in the ribbon.
3. Click on the "Select Data" button in the "Data" group.
4. In the "Select Data Source" dialog box, select the data series you want to modify and click the "Edit" button.
5. In the "Edit Series" dialog box, adjust the settings for the "Series X values", "Series Y values", and "Series Z values" as needed.
6. To increase the number of contours, you can try increasing the number of data points in the "Series X values" and "Series Y values" fields.
7. Click "OK" to apply the changes.