"What exactly do yule logs, mistletoe, evergreen trees, Santa Claus, gift exchanges, decorations, colored lights and general merrymaking have to do with scripture?"
They have nothing directly to do with Scripture or Christmas as far as Catholics are concerned. "Santa Claus" was an invention of the Coca Cola company - another great American cultural export - perhaps you should ask them.
The basis for the Christian era Santa Claus is Bishop Nicholas of Smyrna (4th century A.D.) The Orthodox Church later raised "St. Nicholas" to the position of patron saint of children and seafarers. His day is December 6th.
Coca Cola stock at this point was selling 20,000 shares a penny.
In 1773 St.A.Claus made his American press debut but was never popularized until 1823 with the poem "The night before Christmas" by Clement Clarke Moore. At this point Coca Cola stock had been delisted from the exchanges but reappeared in 1886 with a "New Improved Formula by an Atlanta, Georgia pharmacist.