Advice on publishing a children’s book

I’m working on a children’s picture rhyme book (ages 3 -5) focusing on disability awareness. I’m just looking for tips on format and materials to use.

I’ve finished a first draft, ready to do a second, but want to make sure it’s as ready as can be.

Is there any preference from publishers on what to use for colours (markers, gouache or through adobe), type of paper the illustration should be on, does it need to be the original image or should I get them scanned and what should I do with the text of the book? Should I just put it on with the drawing as I imagine the book looking or should I type it out separately and label the images to match?

I’ve never worked on a book before and all the advice on publisher websites isn’t very clear. I know to get an agent, but I’m waiting until I’m 100% ready to go before I approach one, unless a few people recommend that this is the best thing to do to get more clear advice.