I would cut off the faded blooms so seedpods would not form leaving the stalks as long as possible so the leaves will replenish the bulbs with nutrients. I stop fertilize my plants at the end of June, but you are in CA; I don't know until when you should fertilize your lilies. By all means, water them until the leaves turn brown in fall.

I usually top off my garden with compost and mulch every fall so everything is all set for the following year.