Yes, you can easily do these things with UDM.
For 1), just create a new CSS style like this...
Code:
#udm li a.hover {
text-decoration:none;
}
#udm li a.hover {
text-decoration:underline;
}
For 2) add an id to the menu item in question...
Code:
<ul>
<li id='my_id'><a href='somewhere'>Link here</a></li>
...
</ul>
Then create a custom css rule...
Code:
ul li#my_id {
background-image: url("/path/to/image.gif");
background-repeat:no-repeat;
}
For 3) not 100% sure what you mean, can you elaborate?
Some other links that you may find helpful...
http://www.udm4.com/manual/developme...ernal-imagenav
http://www.udm4.com/manual/customising/classes/