I bought 3 Karhai from my Indian supermarket, they are big enough to do a dish for 6 people.
When I cook an Indian meal I usually have all 3 pans going, One with a base sauce, one with a meat dish and one with a vegetarian dish. I have my Rice cooker going with a rice dish and the oven warm with already cooked Pakora's and Paratha & Chappati
Karhai are very inexpensive, Never wash it, just wipe it clean with Kitchen Roll.
Spices, I would never double up to tablespoons with spices for a dish for 6 people.
The very old Indian Chef who taught me used to say before a lesson *The art of spicing is valued above any other virtue in an Indian cook.*
Every dish is spiced but they never taste the same.
Also remember, Spices have been used for years as Medicines! add to much and you end up with !
a good site to look at is
http://www.greenprophet.com/2010/02/24/17884/middle-eastern-home-remedies/Enjoy