As someone who has adopted 7 cats now, and fostered 3, I think it is really about the preparation for the cats, and the mindset involved that is the issue - there will probably always be a period of adjustment and change to the family routine, but usually it doesn't take too long for everyone to settle into the new way of things.
We had 3 indoor cats when DC was born, in a not so large 2 bed house. I separated off the kitchen with a stair gate early on so that DC1 didn't interfere with their litter trays or food, and introduced the rules about how to treat animals to DC1 from a very early age, so he knew exactly what was expected of him, and respected the cats. The cats always had hideaways that could not be got at by any human without difficulty, so the cats always knew there was somewhere they could go if they needed space as well. It is a strict rule in our house that if the cats are up in their cat trees or in their beds that they should not be disturbed. I wouldn't want to be poked and prodded in my bed, so I don't see that they would either. This has helped with the kids as it is an easy boundary to understand, as is 'no touching when cats are eating their dinner', and 'no shouting at cats', 'don't pick up that cats', etc.
We had 4 cats when DD was born a couple of years later, and again, setting boundaries early on for her and letting her know exactly what was expected of her has worked wonders and everyone gets along very well.
One of our cats was a semi-feral, who we adopted along with a more tame kitten when they were 8 weeks old as the semi-feral needed a catty friend to keep her company and give her confidence, and she wasn't getting attention from adopters, as well as being alienated from the other kittens in her pen. She has settled absolutely fine with both children, and has not been upset at all after the birth of DC2, (although like children, I know all cat's personalities are different). The cats and kids form a sort of pack altogether and are neutral or loving towards each other. They seek each other out for attention or time share just as a multi-cat household generally works.
As long as everyone has their own designated spaces where they can be alone, and there are a good firm set of ground rules I can only see that cats or kittens enhance a family dynamic really, but it is a commitment.
As with all things though it does take a bit of work in the beginning while the dynamic is established, so it is not something to be undertaken lightly.
OP - you sound like you have thought of a lot of this already, so I would absolutely say go for it if you would like to adopt those kittens!