I am putting flourescent fixtures into a remodelled kitchen that is 12'6" x 14'6". Although the room is split by a beam down the width. How many 2X2 fixtures should I use?

I am installing an IKEA overhead light fixture. I have connected white wires to white wires, black to black etc. but the light remains permanently on and will not switch off. There is a spare red wire in the ceiling - is this the switch wire and, if so, to what should I connect it? Also, must the earth wire be connected directly to the green earth wire in the ceiling or can it be safely anchored to the metal fixture in the ceiling as an alternative? Simple questions, I know, but I've recently moved from the UK and everything's different! Any help would be greatly appreciated! Thanks.