A) Dry for usually 4-10 days depending on env RH and temp, bud structure and how fast it airs out, then cure for anywhere from 2-8 weeks depending on preference. The longer the cure the more likely you are to find a nice clean smoke.
B) You can but they won't do much for you if your bud is overly dry or overly moist. They are designed to maintain a certain moisture range as long as the base RH in the container isn't too high or low. They are not a magic solution or fix-all, they have to be used correctly to work correctly.
C) Yes. Uncured bud will taste very planty. You can still smoke it though, and it'll get you high. Curing gives the enzymes time to breakdown all the stuff you don't want to be inhaling. Honestly though, if you use something like a Volcano that uses hot air to vape the bud and it's not on too high of a setting, you probably won't notice a huge difference after the first initial bag - I personally don't. If you burned it with flame though I'm sure it'd smoke harsh af.
The way I see it is this, if you spent 12+ weeks on growing something it only makes sense to let it go the extra 4 or so weeks to finish up and cure to make the best use of all that time spent.
Although what me, and many other growers I know do (and some people will find this criminal), is harvest the bud - all big buds go into cure and all the larf and popcorn nugs go onto my desk so I can vape with my Volcano. If you have the ability to make concentrates like rosen I would do that though, you don't need to cure concentrates and it's a better use of larf and popcorn nugs.
REALLY though, at the end of the day it's your product and your grow and if you wanna smoke it right away then I'm not gonna be the one to tell you you're wrong cause if you just want to get high then you'll get there lol