Questions about submissions

Background: I'm an absolute novice at submitting for publication.

So, I've got some questions about things I've seen in submission guidelines. I've checked all of the earlier posts here and I think I found the answer to one of my questions, but I haven't seen answers to the others:

1) If the guidelines say No unsolicited manuscripts, is it ok to send unsolicited queries? This is the question I've seen answered already, and I think I've interpreted the answer as yes, as long as there is no admonition that only agented submissions are allowed.
2) Does No simultaneous submissions apply to simultaneous queries?
3) If simultaneous submissions are allowed, will it reflect poorly on me if I do submit to several markets at the same time (of course, identifying them as simulaneous submissions)?
4) I've written several (4 so far) picture book stories about the same characters in different situations. Everything that I've read says that I should submit only one manuscript, but should I mention in the cover letter that I envision this as one of a series? Should I give some indication or summary of the storyline of the others?
5) Should I submit all four to four different markets, and if I get a positive response from one, withdraw the others?
6) If I've received a rejection for one of the stories, should I send another one from the same series to the same publisher?

I've got more questions, but I think six is plenty enough for one posting. I will appreciate any and all responses to my naive questions.

Thanks for your answers. I appreciate all the help I can get.