[JWait]

The problem is welcome.tpl is only displayed on the home page and featured products are in every category.

That said, have your tried replacing the call to welcome.tpl in home_main.tpl with featured.tpl?

You may also try removing the part that says $current_category.category eq "" in home_main.tpl where it says

{elseif $main eq "catalog" and $current_category.category eq ""}
{include file="customer/main/welcome.tpl"}

to get the "featured" to display on every page once you have changed the "welcome.tpl" to "featured.tpl"

IMPORTANT! Keep backup copies of any files you change.