It is a hobby that takes a long time i've been collecting for a few years now cacti and own several large loph. willimsii and i couldn't bring my self to eat them. the pic off the one with the fluff is the only one which has hit full maturity and produces 10- 15 seeds a year. while the one with many heads is good for taking one off every year and growing a new one.
they are very easy to take care off, don't water in winter and water once a week in summer, alternating between plain water, and water with a bit of seasol in it to help it along. aswell a ferterlizer low in nitrogen and high in phosphrous is also good once a year.
The only way you could kill it is to over water or fertalize, don't graft it as it will lose its value and magic.