I have a California king and no, it would not fit my regular king frame. But with the right type of adjustable frame you may be able to get it to fit, I ended up building a box under mine with drawers, great amount of storage and a very firm set up..
Absolutely and if you are somewhat tall, you will greatly appreciate the extra length of the California King. Even though it is a bit narrower than a standard King, it is still plenty wide for two.
btw, any adjustable metal frame will accomodate either size.
