As a vague general rule it's true, but my grammar book suggests it's all a bit more complicated than that... :( Eg. "Segovia esta en Espana, al norte de Madrid." It is pretty permanent, still they use estar. Or "Que hora es? - Son las doce y media" It's temporary and yet they use ser. If you say it's Friday today, you use estar, if you say it's Saturday tomorrow you use ser. Confusing.
Anyhow, as I read through the example sentences, I can't really discover a crystal clear logic. I think I just have to learn that in this case you use this, in that case you you use that and don't ask why.
I think it's whimsical, as partita has noted above. But also, it seems, as rspreng indicates, it could be either. "Estar" is used for location (which is often permanent), so the temporary/permanence divide is no clear division of these verbs.
That said, my grammar book lists "soy casado" (I am married) as being the correct way to say that phrase. But in a grammar lesson on the online LoMasTV, the teacher says, "Estoy casado," and adds with a wink that she's married hoy, but mañana, who knows?
Similarly, in my grammar book: "Ella es bonita," = She is pretty (by nature). "Ella está bonita" = She is pretty right now. "Es borracho" = He's a drunk (as a characteristic); Está borracho = He's drunk (right now). And many more.
I just found a good webpage that discusses both estar and ser for casado: http://spanish.about.com/od/usingparticularverbs/a/casado.htm
You need to use object pronouns (me, you, him, her, it, us, them) after a preposition. This is a pretty strict rule. You do hear between she and I, but my usage dictionary says it should be avoided. I've never heard between you and he or between she and he from a native speaker. (Doesn't mean there aren't people who use it, but it really isn't terribly standard.)
An excerpt from http://blog.dictionary.com/youandme/ :
The “you and me” problem is confusing when there are two objects, as in the sentence “Thanks for inviting my husband and I to dinner.” If you are ever unsure, here’s a simple trick. Omit the first person and see how it sounds. If you said, “Thanks for inviting I to dinner,” it sounds wrong. Without two people, it is easier to use your ear to hear if “I” or “me” is grammatically correct.
Well, in a sense, I am among you and him IS acceptable. But the word between (in both Eng and Span) can only be used when sth is between 2 other things. Among cannot be used with 2 things. So if the sentence were Estoy entre la familia, you would translate it as among instead of between. It's really just a matter of understanding the difference between "between" and "among" in English first.
When this is spoken quickly, the second "e" in "entre"" sounds like the most common vowel SOUND (not letter ) in English, "UH" . Is it just the computer voice, or does Spanish change vowel sounds at the end of words when speaking quickly ? (this doesn't change the meaning, so native speakers may not know they do it). I hear this also in some of the sentences with nosotro/nosotra, where it can be hard to tell the difference - not exactly the UH but neither a strong o or a strong a.
The pronouns are the object of the preposition between, not the copulative verb. By the way, the rule in English the way it is used is to use an object pronoun immediately after the verb. It's me is MUCH more common than it's I. The whole copulative verbs take subject pronouns rule is part of a very old attempt to make English like Latin. It's me goes back to Chaucer, WAAAAY before grammarians got involved with how we SHOULD speak English.
Between is a preposition. Prepositions are followed by object pronouns. He is a subject pronoun. Between you and he, while often used, is wrong. Think about it. Would you say between we? If most English speakers are saying between you and him, they are saying it correctly.