Look around in the areas with the South Asian community (Pakistani/Indian/Bangladeshi) to find ethnic stores for specialty spices.
Whatever recipe you use, reduce the ingredients proportionately like you would for any other recipe.
The only reason for a large pot is to make it easier to mix the rice and gravy after it's cooked. If you don't have a large pot available, you can use a wide pan (of adequate height) with a lid. Avoid using narrow stock pots. It will be difficult to mix the rice up in a small pot without breaking the rice.
You can even find boxed spice mixes in the ethnic stores to save the pain of buying individual spices. You can find these on Amazon as well.