Well I've had some of my anemones for a pretty long time 2.5 to 3 years. In their life cycle that's just a drop in the bucket but, they seem to thrive and have reproduced in my tanks ,"that's not always a good thing by the way somtimes they do it due to stresses,". Metal halide is an absolute must for most species," the exception being tubes they don't need the light at all and aren't really a true anemone. " They also need a tank that is at least 8 monts old and very stable no c.c. or fish that will pick at them.
Please listen to what wastememphis said about clowns beating them to death they do a lot of the time. I would also limit them to 1 or maybe 2 varieties per tank ,"rose and green bta being counted as different types." That absolutly must be feed I feed my roses every other day with a bit of meaty raw sea food and on the off days I dose with phyto/zoe plancton they also need dietary suppliments like selcon for example.
I'm not sure that they aboslutly need a host I have one tomato clown and 12 roses ," at last count and I count every day
" It seems to host mostly in 2 or 3 of them and ignore the rest unless the giant hand comes into the tank. If you must get a rose please get a c.b. one from a trusted source they don't have all the bleaching collection issues that a lot of the wild caught ones do. Also be harsh when selecting if they are ANY signs of bleaching a ripped foot open mouth etc reject it. The chances of someone with a lot of experience nursing anything more than a slight bleaching back to health are really low. Also if you want multiple anemones make sure that they are cloens of one individual other wise if they clump up in a colony even the same species will often times sting each other to death.
My honest advise to you would be to start out with one of the anemones that don't host clowns like a rock or a tube anemone. Rock being the first choice because it won't reproduce in your tank won't move around much and it can take the bio-chemical weapons produced by your roses when you get them down the road. Always keep their bio-chemical activities in mind if you have other inverts like corals etc in the tank . You'll need to run charcoal or other carbon filtration to deal with these issues.
They really are great critters but, they aren't for every set up out there. IMHO you really should build the tank with the anems in mind that's more true for some varieties than others of course.
I hope this helps you and please be sure that you really want a creature that your grand children will inherit from you. They live longer than parrots and need VERY stable conditions that also means if you get them and something gets out of whack you'll have to adjust your conditions back to normal very slowly.
chris