If we need at least 1500 mg of calcium, what would you eat daily to supply
this amount?

If I want to supplement calcium what is the most bioavailable calcium?

I remember reading somewhere that calcium citrate (most popular supplement
form) is not really that bioavailable and therefore poorly absorbed.  I think
calcium citrate is supposed to be the best form, but have no corroboration.
Also, aren't you supposed o take calcium supplements before sleep???