Dried and powdered chillies are used for different reasons, and as for compensating with equivalent amounts of powder it's always difficult to be accurate here, gagomes, as dried Kashmiri chillies (and all dried chillies) vary in size, but from my experience in grinding them myself, I'd say that one decent-sized (large) dry Kashmiri chilli will give you around half a teaspoon of powder (maybe a little more).
However, don't forget that the game changes as soon as you turn a dried chilli into powder!
Dried chillies are used to impart a more subtle flavour and heat hit to dishes, whereas powder is used to give more intensity and heat. And, of course, for colour - especially in the case of Kashmiri chillies.
But Kashmiri chillies, whether in dried or powdered form, aren't particularly hot, so you've got a bit of leeway for experimentation - and even if you do use a little too much you're not going to blow your head off with Kashmiris.
I've never used jaggery (which is an unrefined cane suger) so can't comment on the smell. I'm sure others here will be able to help.
Be careful how much cardamom powder (elaichi) you use. The proper stuff is made from grinding just the seeds from the cardamom pod, and a little goes a long way. (It's the same deal as with dried vs powdered chillies).
Apart from it being seriously expensive, too much is going to completely overpower a dish, whereas in recipes calling for whole cardamoms you're just looking for that subtle underlying flavour.
So, again, use with care.
Bottom line is that if recipes call for dried whole spices, and you want to replicate the dish as described in the recipe, then that's really what you should use.
That's not to say if you don't do that it won't turn out well. It will just be a little different.
Maybe brilliantly so!
