About bath bombs, from a BB newbie

[cybersix]

Hi all, this is my very first time posting in this section, so I hope to put my question in the right place!

I made some bath bombs and they turned out good, now I have some questions if you can help:

1) the recipe I used is this:

Dry Ingredients:

• 1 cup baking soda
  
• 1/2 cup citric acid (do not substitute ascorbic acid)
  
• 1/2 cup corn starch

Wet Ingredients:

• 2 1/2 T. sweet almond oil
  
• 3/4 T. aloe water
  
• 1 teaspoon of fragrance oil

How do you find this recipe? Is it good? I don't have access to many ingredients, but can bath boms be enriched with something else?

2)How long can be they kept on the shelf?

3)One bomb is about 2 1/2 oz weight, what is the average usage for a bath? One or two? I know lush boms and many other are big, but how big?

Thanks in advance!