A. Unless you're breeding with a Pokemon from another game, the chances are still the same. If you're breeding two Pokemon from different regions (like Japanese Ditto, English Beldum), then the chances are cut down to ~1/2000 iirc. The only benefit to breeding two same region ones is that it's probably faster, and you don't have to worry about finding the Pokemon and accidentally killing it.
B. I can't answer this one, because I've never bred a shiny tbh. But say that it takes you 20 minutes to collect 5 eggs and hatch them, that's 32,000 minutes to hatch 8000 eggs, or just over 22 days. But you're obviously not going to be breeding nonstop so it'll take much longer than that in reality to even the odds. But you may run across one on the first egg...or you may breed for 6 month in every free second and never find one. It's all up to your luck.
Not all men...
Are all men stupid?
That's right.