How do I make it that the 4 options that are for sale in the new for december section come out of that box and may be go into another that says products for sale or alternativley just have them appear on the page below the welcome message?
Not positive what you are seeking here but there are several options available in the admin

See: admin > config > layout settings > Categories - Always Show on Main Page
admin > config > layout settings > Main Page - Opens with Category

See if these might provide what you want and you can eliminate the display of the new, featured, and others in
admin > config > index listing > Show New Products on Main Page
and others...check the options & resulting display
How can I make the page loose the 3rd column which was on the right so that it makes the page looked more centred?
admin > config > layout settings > Column Right Status - Global > set to "0"