I have ¼" copper tubing coming up from basement and ¼" copper tubing coming from the back of the fridge. What do I need to hook the two together? (Guy at the Home Depot was useless. Sold me the wrong part.) I have about 2 extra feet of copper tubing, should I add more?

I'd buy a frig filter installation kit. The filter is a good idea for better ice and it will add a bit of lenghth to your tubing. I usually add about four or five feet of tubing to make moving the frig easier, eventually you'll need to be back there. You can stick with 1/4" coper or transition to semi-claer plastic tubing. Most guy are more helpful than the one you met, maybe try a different clerk next time.