i enjoy riding at night. spares me from those nasty sunglasses/helmet straps tans i get from morning rides.
i use a planet bike superflash for the rear and a magicshine for the front. the magicshine is overkill for riding in the city (and well-lit streets in general) but is absolutely necessary for bike paths, river trails, or otherwise "desolate" mountain/canyon roads.
as confident as i am with night riding, i will admit that i did find myself lost the other night in hollywood hills. a lot of narrow, snaking roads, few cars/people, and it was cold, dark and windy. these factors started bothering me psychologically but i eventually found my way up to the hollywood sign. the last stretch was an interesting experience, as i was riding in near-darkness and i felt like i had the whole mountain to myself. but overall, i never felt unsafe or bothered by cars.
as for getting from irvine to anaheim hills, the most straightforward route is irvine center to sand canyon to portola to jamboree/santiago cyn to cannon. or you could take irvine ctr to jeffrey to walnut and get to anaheim hills via tustin.