I personally like coconut oil.
CBD binds to fat.
coconut oil has the highest fat content. (around 80% vs olive oil 20%)
Also coconut oil becomes a solid at 75f which means you can have it as a solid or a liquid.
Want solid? Put it in the fridge.
Want a liquid? Run the sealed container under hot water.
The dosage part is much more tricky.
I use the formula for finding the flowers CBD percentage and then guess a little.
if it's "18% CBD flower" I multiply the 18% by 0.877 to get the max active CBD which is 15.78.
(Why 0.877? I dunno, that's what they said to use
This means in theory each gram of the "18% CBD flower" contains 157.8mg of CBD (15.78% of 1000mg / 1000mg = 1 gram)
You aren't going to be able to extract all of that CBD from the flower in your kitchen so I'd take a guess.
If I ran 10 grams of "18% CBD flower" (potentially 1578mgs of CBD) i'd just call it an even 1000mg's of CBD
With THC I would rather overestimate the dosage than underestimate it so I would call it 1400mg's just in case.
CBD doesn't make people flip out and go to the emergency room so it's OK to be a little off.