I find they're quite easy to deal with. If you expose the rhizomes just cut them leaving enough roots on each piece. They're very forgiving provided you don't stress them with too much direct sun and lack of water. Those rhizomes allow (for a fern) a bit of drought tolerance. In my garden I have several different types but one looks identical to yours. It flourishes in the wet season but completely dries out and loses all its fronds for about 4 months during the dry season. When the wet season returns it comes back with a vengeance. They are tough.

I realize this may be too late... but yellow leaves usually mean plants are TOO wet and that you have root rot. Maybe let it dry out a bit more between waterings... also, if you’re fertlizing it, stop. That could also be causing this.

I have found that Anigozanthos is quite long lived especially in neglected areas or areas that did not and do not receive wonderfully rich organic compost applications. That first photo is a commercial shopping center bed that was planted about a decade ago ( Hopmonk Brewery in Novato ) . It receives some commercial level maintenance attention but it is not lovingly cared for by a home gardener ( no disrespect to commercially cared for landscape companies) . The second image is of a residential project in Belvedere that was also planted about 10 years ago. It has not received 'attention to detail' maintenance over the years yet the Anigozanthos is doing well . The Leucadendron Jesters have not been adequately pruned and are out of scale now and looking rangey. I have some 'neglectful' areas in my own experimental home garden. Some of the kangaroo paws are going on 15 years old and still bloom despite the poor soil and infringing shade from the overhead oak trees . I believe that true to their native habitat that the Anigozanthos prefers lean soil fertility conditions and good drainage for it to be successful in the long run. Good gardening to you.

Yes, you should. I don't know about kangaroo paws (aren't they a CA native?) but I'm quite familiar with cutting into / planting in the delightful and rock-ridden SouCal clay pan. I'd contact a local garden club through their website to see if they have tips (normally I'd suggest you join a C&S club or at least attend a meeting, but they're not happening now). Short answer - no sand. NONE, as it's not useful in this situation. The best would be small gravel/decomposed granite and pumice, along with some sieved top soil to use as soil amendments - what you want is some of that clay in the mix, but mostly the other things, particularly the DG and/or pumice. Amend the yard as you need to - the planting locations need it, not necessarily all of it. Oh, and get a digging bar if you're going to do a lot of this. It's invaluable in punching planting places into the ground. I think your chalk plants are Senecios.