2questions about the style

no matches... T.T

/* 3.2 Underline on hover for links in headers and main menu */

#brdmenu A:hover, .blockpost H2 A:hover {TEXT-DECORATION: underline}

this is in oxygen.css

change that  to
/* 3.2 Underline on hover for links in headers and main menu */

#brdmenu A:hover, .blockpost H2 A:hover {TEXT-DECORATION: none}

search for this then TEXT-DECORATION:

It's in the stylesheet for whichever style you are using - /style/Lithium.css, /style/Oxygen.css or whatever.  If you offer your users a choice of styles, you'd need to alter each one individually.

Just scroll down a little to the section:
/* 3. LINKS */
and in 3.2, as quaker says, change
{TEXT-DECORATION: underline}
to
{TEXT-DECORATION: none}

In that case I'm afraid that all I can say is "Sorry, you need someone with a better understanding of things than me". 

What quaker suggested is exactly what I did with my own forum when I set it up after prodding around the code and finding that bit, and it worked for me, but beyond that I'm lost.