I just found your website, and find it to be very helpful. However, I haven’t been able to find the answer to one particular question I have: exactly how does one format the manuscript for a RHYMING picture book - that is, one with stanzas. Do I format it like a poem (single spaced within a stanza, and double spaced between stanzas), or double spaced with 4 spaces between stanzas. Your answer would be GREATLY appreciated.It doesn't matter. Leaving a break where you anticipate page breaks might be a good idea, and would make sure you've considered how the manuscript will page out in a standard picture book length.
I would suggest you don't format it in running text, like that's going to make the rhyme scheme more subtle or something. Remember that many editors are very sensitive and skittish around rhymed text, so it's not a good idea to present them with something that doesn't look like it's going to rhyme but surprise! it does. To many editors, it's like finding a spider in a candy box. Shock and horror? Not the response you're going for.
Yes, some editors like spiders. But even so, be sure there's a good reason for the manuscript to be in rhyme. "I like it that way" is not good enough.