If it's not what you're looking for you need to be a bit more descriptive! - If you look through the bbcode element of pun you can probably overwrite the url creation elements to make the link label 'link' (or whatever text you want), currently the link label is set to the url in the final html markup.
As to styling; my friend is having some troubles with it...
Um, it's a big old topic to just give help on, study the Oxygen theme, copy it and start making changes and see what happens. Generally all you need to change is the Oxygen_cs.css which is the colours. If you copy the Oxygen directory and rename it to your new theme name all you really need to do is then rename anything with Oxygen in it to your theme name.
Then I'm afraid it's down to fiddling!