Type of salt to use for Indian recipes
You can use Kosher salt or sea salt or even table salt but keep in mind that they are interchangeable by weight NOT volume. Volumetric measurements fail because of different sizes and shapes of salt crystals. Kosher salt crystals are, as you pointed out, larger and end up with larger gaps between the crystals when measured by volume than the smaller table salt crystals that settle together more closely (consider the tiny spaces between grains of sands versus the larger spaces between pieces of gravel). This means that a teaspoon of table salt actually contains more salt than a teaspoon of kosher salt. This means that if your recipe calls for a teaspoon of table salt you will need to use more than a teaspoon of kosher salt. They will dissolve equally well. As to when to add salt, add minimally at first then adjust the salt to taste at the end. 

Edited to add: you can find a rough conversion of volumetric measurements of different salts here: http://www.mortonsalt.com/for-your-home/culinary-salts/salt-conversion-chart