seperating Sticky's from regular threads

The easiest way to make a distinction is to give sticky topics a different background colour, perhaps one shade darker than the normal background colour. Just add this to your colour scheme stylesheet.
.pun tr.isticky td {background-color: whatever}

Adding a horizontal line under the last sticky is more difficult because you first have to identify which is the last sticky and that means adding a seperate class to the row by changing the php in the loop which generates it.