Hi Eli Elaine, tricky question to answer.
Nut grass, I have eliminated however need to continually monitor for reestablishment and remove. How did I do it, By continual physical digging it out. You need to do a section at a time amd leave the bed with only mulch on it and as the grass comes through dig it out . Do a quick dig through when you first start and get as much as you can,. Then mulch it. Then each time you will get less and less till eventually there will be the deep down survivor nuts. Each time you chase them you will get more precise on getting the individual nuts.
With bindis, I have the impression that they grow on bare compacted soil. So change the soil conditions and they should lessen. There is a salt spray that you cannot make up and I am afraid I have forgotten the ingredients which is annoying as I have some bindis to get on top of myself.
Hope this helps.
Tom