I did my first pastrami a month ago and have the second one 3 days in the brine so far. I did a bunch of research but only have done beef twice. But I've done 4 batches of pork belly bacon and 4-5 batches of back bacon.
1. I haven't had any meat spoil on me, but I hear you will know it by the smell.
2. King's Rub Sounds Great. The key ingredients are the pepper and the coriander. After that add what you like or think will taste good.
3. Brine time varied alot in my research too: 3 days to 3 weeks. But the general rule is that it depends on the concentration on the brine and how big a piece meat you are working with. I have a 4.5lb flat cut in the fridge that's maybe 2-2.5 inches thick at the thickest. I'm going pull it out of the brine Thursday and smoke it Friday cause that works for my schedule. But I'd guess that it would be cured in about 4 days. If it were a whole packer brisket, I'd let it go a minimum of 10 days. As long as your using a good brine, you can let it go longer. This is one of the ways they used to preserve the meat until it was needed for a meal. Before refrigeration, it might spend 3 weeks in the brine as a way to store it.
4. Traditionally the pastrami is steamed after smoking so you want to smoke it for 3-4 hours to 150 internal and then foil it to finish cooking it to 170 internal. Let it cool in the foil so the maximum amount of juices are reabsorbed. I run the smoker at 180-200 so that it will take a few hours to get the meat to 150. (same technique I use for bacon) After I foil it, I might put it into a 250 degree oven to finish. Last batch I actually steamed, but I think its easier to throw in the oven.