False. It's not illogical, we just don't know the information yet. It's very possible that not releasing himself from the jutsu has benefits. We know that Edo Tensei has many benefits: invincibility and regeneration, immortality, at least some measure of increased chakra capacity (and maybe infinite chakra, as has been suggested). Releasing himself from the jutsu may make some or all of these benefits disappear. Madara might not be invincible anymore, for instance.
Also, there's no reason to suspect that Madara was ABLE to release himself. Before Kabuto released the technique, Madara was under Kabuto's control. That control was weakened for various reasons, but it was control none the less. Remember how, in the moments before he disappeared, Dan was able to control his own movements again? There was a brief window where Madara was able to do the same, and he used that window to release himself.
This is all speculation. We don't know the answers yet because Kishi didn't tell us. You're just guessing, and your guess leads to the "illogical" behavior you describe above. If you guess the other way, that Madara is now limited from being released from the technique, then the answer to your first question is not illogical. If your premise, that Madara has all the same benefits as he had, and that leads to the contradiction that he should have released himself earlier, then your premise must be wrong.
We don't know if he is "bound" to anything any more. We know that his soul has not left after being released, but we don't know if it's something like a seal creating a permanent binding or whether it's just force of will or some other technique. Minato's soul cannot be summoned because it is in a seal. Madara's soul might not be in anything so strong and may still be able to be summoned against his will (for anybody willing and able to do such a thing). We also don't know if the Rinnegan's Naraka path is like a summoning technique or if it's something different and more fundamental than that (and therefore might not respect seals on souls).
When Nagato used Rinne Tensei, Tobi required that "he was supposed to use that for me", not "he was supposed to use that for the real Madara". There's no evidence that Tobi ever intended to revive Madara, and in fact he seemed upset that Kabuto had done it. Notice also that Nagato's motivations, such as the reason why he was collecting the Bijuu, were different from Tobi's secret motivations (the Moon's Eye Plan). There's no reason to suspect that Tobi would have done what Madara wanted, even if that was the publically-agreed "plan". The simplest answer is that Tobi didn't want Madara to be revived at all: Tobi had the Bijuu and Tobi has the sharingan (and now the Rinnegan), and Tobi wanted to rule the world by himself.
Your definition of "plausible" is different from what I am used to. Madara has a plan for world domination that requires careful and concerted effort over many years, meticulous planning, the manipulation of various powerful ninjas and even entire nations, and control over the primordial forces of the universe including the Bijuu and the powers of life and death itself. You think it's "plausible" that he just gives up and goes away after everything he's put into this plan so far? That's absurd.
Madara is going to be defeated in battle and he is going to be defeated by forces representing the opposite ideology. Madara represents the Uchiha curse of hatred, and the evil desire for world domination. He will be opposed and ultimately defeated by people representing the will of fire, and the freedom and protection of mankind. In short, Madara will be defeated by Naruto and Naruto's allies. This is the thematic thrust of the entire manga, at least since part 2: That true strength comes from protecting people you care about, and Naruto is the most selfless protector on the battlefield. Madara has nobody to protect. Naruto has everybody to protect. The real validation of the philosophy of the entire manga is that Naruto's way produces real power, while Madara's way does not. Tobi is a similar person, dominated by the curse of hatred and using people as pawns and tools (and sources of body parts). He will ultimately be defeated by the forces of the Will of Fire also.
False. As I mentioned in response to your first question, there's ZERO EVIDENCE that Madara was able to release himself at any time. Kabuto was controlling his movements, to a degree, even if he did leave Madara with some level of autonomy. Also, there's a very real chance that releasing himself means Madara loses some of the benefits of invincibility and unlimited chakra, and he wouldn't have wanted to be released from that yet.
Why does Madara fight the Kage? There are several good reasons. First, he started the fight because Kabuto told him to. Kabuto was in control, and he tells the zombies what to do. Some of the zombies (Deidara, Kakuzu, Gin/Kin brothers) are willing to go along with this path. Some (Dan, Asuma, Chiyo, Hizashi, Haku) were unwilling pawns and were FORCED to do what Kabuto wanted anyway. Sasori was able to break out of the binding because he had a weaker binding and his soul found peace. Madara hasn't had that kind of transformation yet.
Second, Madara did indeed want to test his new abilities, especially since his body has been "enhanced" beyond what he remembered it to be. Fighting the kage is seen as being a worthy challenge to test himself with. This mirrors very strongly the way Sasuke wanted challenges to test his new abilities at each step. That's why Sasuke was so willing to fight Killer Bee and later why he was so willing to fight all the kage. It's why he's been slaughtering Zetsu clones. It's even why Sasuke was willing to kill Karin: To test himself and increase his own strength at the expense of others.
Third, the Moon's Eye Plan and the infinite tsukuyomi requires the capture of all nine bijuu and the assembly of the 10-tails. Madara and Tobi do not have these. We know that sealing a Bijuu into the Gedo Mazo is a technique that takes up to three days, so they are going to need some time of peace to do it, which means they also need to defeat most of the allied shinobi forces to give themselves enough time.
Fourth, Madara was summoned to the battlefield by Kabuto. He doesn't know who Kabuto is or where Kabuto is located. He either doesn't know Tobi or hasn't acknowledged him. He doesn't know where Tobi is. Or where Naruto and Killer Bee are. What he does know is that the kage are right in front of them, and defeating them will be a major help in the war effort, both in decreasing the total strength of the allied army and in demoralizing the remaining troops. It's good strategy to kill the leaders when you have the chance, and Madara knows this.
False, for all the reasons I mentioned above. Plus, it creates a counter-point for Tobi, since we know that both Madara and Tobi cannot use the Infinite Tsukuyomi together, and we're not even certain that Tobi is planning to follow this course or if he lied about that too (to "prove" that he was Madara, when he clearly isn't). We now have three enemies (Tobi, Madara and Sasuke) with possibly different motivations. This leads to a very possible and very interesting situation where the allies are defeated, but the enemies ultimately defeat each other by pursuing different goals. This in turn may lead to something like Sasuke's redemption and the cleansing of the Uchiha name.