Stay Away from the Cacique chorizo - it is a typical NOB downscale lymph-node-and-salivary-gland intensive product. I can't recall if they make a 'longaniza' style which is slightly aged/cured and contains non-offal cuts - a better alternative.
EDIT - all of the other California brands (El Mexicano, Reynaldos, Carmelita, etc) make it this way. Farmer John brand has a 'premium' chorizo that doesn't show nodes and glands on the ingredient list, but they now have cheaper 'tradicional' product that does.
Yes, they are easily found, even in mainstream grocery stores.
Keil's carries them, most of the Henry's carry Cacique. I don't think you'll have too much problem finding them. Most stores carry at least the Cotija. Pancho Villa and Northgate carry a much wider selection of the product line
I like Cacique prodcuts, they're pretty good. Not as good, of course, as what you'd actually purchase in Mexico, but they work well for Mexican cooking this side of the border.
I've not tried their chorizo, but I have used their cheeses and cremas pretty extensively with good results.
3245 El Cajon Blvd, San Diego, CA 92104