As they get older, you will understand how they work better, as will they, and it will get easier. In the meantime, read up about sensory sensitivity, there is a good video on the Sheffield children's hospital website which explains the basics. For people with adhd, it is usually around providing extra sensory input stuff to help them regulate themselves, e.g eighteen blankets, indoor climbing frame, stretchy bag, wobble board etc.
Then like others have said, make sure you cover the basics as people with adhd often have difficulty working out what is wrong I
Ie can't tell if they are hot, cold, hungry, cross, safmd, happy, tired etc. So you need to help them learn to work through a list of options if they can't tell which one it is.
Anxiety is really hard. Not sure how to help with this other than reassuring them that it is normal to worry about things and that it will be OK.
Also I found that dropping all the rules that arent really important for your family might reduce the stress. E. G. People should wear shoes in the garden but is it really worth the trade off of constant nagging vs cleaning the floor slightly more often? Or maybe swapping siting at the table door meals with standing at the table if its easier for the kids.