Early 70's was "peace man", with lots of orange and browns for decor, psychaedelic patterns and ban the bomb symbols.
Later on into the mid 70's, glam rock took over in a big way and platform boots made an entry.
'76 onwards was punk, so the 70's had quite a mixture of styles and fashions, all in all.
Here in the UK, 70's party food consisted of prawn cocktails, cocktail sticks with either a cube of cheese and a cube of pineapple stuck on it, or a small folded piece of ham with a pickled onion stuck together, and quiche lorraine.
There were always loads of triangular sandwiches with boring fillings and stale crusts, and sickly puddings like black forest gateaux.
Music? Moving through the 70's, it was transcendental stuff (Beatles, Hendrix etc), then reggae, motown, glam (T.Rex, Sweet etc.), disco then punk, starting with groups like the undertones, Ramones and the Pistols.
Sounds like you're going to have fun. Can I get a ticket?