wow, so many questions,
generally,I agree with all that others have already written. Infused oils not only contribute to color, they work as well, probably less in a rinse-off product than in a leave-on lotion, cream or oil.
There is a wonderful soothing After-sun oil tutorials on soap queen and at least one for making lip balm with infused oil, Anne-Marie reveals some interesting and useful tips and tricks.
Generally, you can make cold infusion, hot infusion or a combination of the both.
The best/most useful oil infusions are, calendula, st.John's worth, Arnica, Yarrow, nettle. I have recently prepared a chili infusion, it's not ripe yet, I'll inform you about it later. Besides the res color, chili is a warming herb/spice and should be applied, for example in massage oils for soar muscles or for rheumatoid pains.
For color contribution is CP-soap I rather apply tea (infusion in water) than in oil, I have some fantastic samples in which even the herb contributes to the smell, it's applicable specially to spices such as Cinnamon, Cardamom, Peppermint or chamomile
The choice of carrier oil depends on the price and stability of the oil. Jojoba is of course the best choice (because of thermal stability and shelf-life), it's up to you if you choose it because of the price. A wonderful choice with low price is Soy oil, other oils usually used are olive oil and sunflower oil. You should apply an oil with low inherent color and odor, you can not, for example apply raw avocado oil or tamanu oil because of their intensive color and odor.
I hope it could be helpful a little, the rest is a matter of experience, try in low volumes for the first couple of experiences. No panic, just try it
