I make cheese, and have spoken to some of you here about that as well. Producing commercial dairy products blows away the health and safety regulations in beer and wine making. Think it is hard putting a fermented grape in a bottle for sale, try something that comes out of the backend of a live animal...
Even in California, the beautiful tasting room all done up in oak often has nothing to do with the beautiful vineyards outside.
That's mostly all there is to it. Reading up, will teach you what to expect the starter to look like, how to troubleshoot, and how to turn the starter into bread.
I like the simplicity of flour, water, salt. (And air, time and kneading.) The simplicity leaves no room for covering up mistakes like cakes allow you to do.
> How did you ensure you were catching something useable and not something you didn't want in your bread?
Humanity is very lucky that the most probably natural occurring fermentation in grain dough is not only perfectly safe, it also improves taste, nutrition, digestibility and shelf-life of your bread.
Your nose will tell you if something is off. I think mold is the most common invader. But even mold will have a hard time in a healthy sourdough, because the low pH (=high acidity) and some enzymes keep the symbiosis of yeast and lactobacillus exceptionally stable.
It's a hell of advertisement for the shop, though!
Edit: and now that I think about the other things:
Regarding 1 and 2: some hop varities have mildew problems, and bad weather has negative influence on the growth and other things like alpha acid, so bad weather can have quite the impact on hop quality and availability. The 2013 hop harvest in Germany was quite the disaster, apparently. AA% is a lot lower, and young plants of some new breeds got way too much water.
*very broadly, no you don't need to tell me about DFH 120 minute or what have you.
Heady Topper, for example, is pure hop madness.
There are good west coast breweries but the culture created a style and has stuck to it like gospel. Variety is what makes beer fun.
[1] http://www.agha.org.au/cms/uploads/images/Grape%20harvesting...