How many spells? Countless. Someone made up all the ones which you will find now, many people make theor own in stead of using one pre-made, and anyone can make their own. That makes the number of spells in existance limitless, as the variables are undeterminable.
A spell is not what is magic; it is a ritual to direct one's energies and intention towards the purpose for which they want a magical result. It opens up the possibility of what may be done as a spell or ritual to basically anything.