I think supporting your kids at home should be focused on learning through play mostly. Particularly at the ages of them just now. I agree with previous posts about 10 mins max on "proper homework" and the other ways you are doing seem fine as well. I would stop myself from worrying about this too much as this will impact on the kids without you realising and could make them worry themselves.
At that age I used to get involved more often in imaginative play like:
Homemade shops where we pulled lots of groceries out the kitchen and labelled them with prices / numbers before buying them from each other. Much more fun than plastic goods. Maybe setting up a picnic area in the room with blankets for after the shop play to eat our "shopping". Lots of fun but also learning without them realising. How much is such and such etc..... For your older one bringing out change money and playing with the money in the context of the "shop".
Post Offices - (this was one of my childhood favourites I then played with my child) Selection of pens, stampers, ink pad, writing paper and stamps if you can. Someone being in charge of the post office counting the pretend letters, stamps etc while the other must write / design their letter and "attend" the play post office to have it stamped and sent away. Even attach real stamps and have a walk to post a letter to you or back to themselves. Again lots of fun and learning at the same time. Especially when the letter falls back through the door from the postman.
Cafes - have all the teddies sat at little pretend tables and work on serving, again with pen and paper. Work together to write down the order for the "Dog, cat etc. If someone wants a milkshake write a M for milkshake or make up menus where they have to tick on the sheet the order you say out loud. Reading without realising.
Play these games at a very basic level of understanding to begin with and build up complexity based on what you think is mostly fun but a little educational. My daughter thrived with this sort of thing but didn't like the sit down homework for too long.
You also can't underestimate the worth of messy play at this age either. Painting letters on large sheets of paper, making banners, names made from clay then baking it.
Find books that interest them along side the school books and read the same ones regularly to them. They will build up knowledge and words from listening to the books regularly without realising. I could literally read the books with my eyes shut from the amount of times we read them but it's now paid off because she now loves to read and is really competent even though for years she would only listen to the stories.
This is only some things that worked for us as a family and you just need to take ideas that suit you as a family and find your own balance but please try not to worry (which is also easier said than done)
Good luck.