the leaves have holes in them and turning yellow

Is this a problem? Is there something wrong? or is it normal? If not is there a way i can fix it?

Doug says sounds pretty normal to me. The snails get to eat the leaves and create holes. Not much you can do about snails unless you poison the entire pond (not recommended).

Yellowing leaves are old water lily leaves and that's what they do. They age - go yellow and die. If you're feeding properly, new leaves will be produced and the plant keeps growing.

Do remove the yellowing leaves or they'll sink to the bottom of the pond where they help turn the bottom into the most "amazing fragrance" of pond gunk you can imagine. :-)