Fortunately you don't have to simulate the fog (and it's not salty)... you just have to water more to make up for the fact that the tree is not getting any water from the fog... of course it's going to need even more water because it's baking in the sun all summer while it's northern cousins are...
This is an excellent resource about caring for Redwoods. It will give you some ideas about how much to water and how to amend the soil.
http://www.mountainview.gov/civicax/filebank/blobdload.aspx?BlobID=12426
That is a good question... My first thought is to duplicate the rainfall that your redwood would receive if it were in a place where they typically grow. In my town (Mill Valley) we get about 40 inches of rain per year. Mostly in the fall and winter...
Redwoods like water... a lot of it. They grow best near creeks in areas that get 40 inches of rain per year, with mild weather and heavy fog. In drought conditions they will "top themselves" so that they don't have to push water from the roots all the way to the top of the tree. Then when the...
Coastal redwoods can live 2,000 years or more. Hyperion (the tallest redwood at 379 feet) is estimated to be about 800 years old. Most coastal redwoods in neighborhoods are just "babies" compared to how big they will be in another 50 to 100 years.
Fascinating thing about the redwoods... ALL of the tallest ones appear to have lost their top at some point (e.g. they were naturally topped), most of them multiple times. When a redwood loses its top it responds by sending out multiple reiterated trunks to form a magnificent crown structure...