For 1 and 2, you'll need to edit your HTML file and your external CSS file. These are independent of the UDM4 code.
For #3, one way to do this would be to specify a width on the entire menu that forces a wrap.
For example. Let's say your menu has 10 items. The first 5 have a total width of 480px. You could set your entire menu width to be 480px, then the remaining items would wrap to the next row.
To see an example of this, check out this link:
http://www.udm4.com/demos/horizontal...ive-center.php
Forum wraps onto a new row.