I'm in Wisconsin so I have no idea (specifically) what California soils are like, but is it common to amend the soil for wine grapes? Will you continue to amend after the initial application?
What I have been told is that the limestone should be a one time thing to adjust the Ph. Most people in Paso Robles have to adjust their Ph the other way (alkaline soil) and use sulfur which apparently is a multi year process.
Other amendments aren't unusual - compost is pretty normal or gypsum if you have heavy clay.
I see virtually all growers here adding compost at the end of the season. Cover crops are also pretty normal - usually some combination of things like barley, bell's beans, crimson clover.