Which side would the Numidians be on? Did they have any especial love for Carthage? Or would they just join the likely winner?
I remember reading somewhere that the Carthaginians didn't employ war elephants until they encountered them against Pyrrhus.
Because Cyrus did pay attention to administration - setting up the satrapy system, for example - Alexander didn't (again, leaving for India without so much as appointing a viceroy to handle anything that comes up while he's out of contact).
Comparing the two is like comparing porcupines and platypuses.
You mean, the same exact satrapy system that Alexander had inherited and employed when he took over the reigns of the Persian Empire? Perhaps he assumed that the existing system, since it worked well for the Persians, would work well for his needs. Obviously his time in India proved him wrong, and the fact of the matter is, we just don't know what he was going to do to fix it, other than the changes he made (as someone else explained).
1) Alexander killed men whether they were his rivals or not because he saw rivals everywhere.
Do you have any other examples, rather than Parmenion/Philotas and Cleitus? You continue to say this, but haven't given any other examples than these two incident, one pre-meditated from the beginning of his reign, the other a drunken rage incident.
2) More of a general than a king describes some rulers, but not all. And Augustus, for example, didn't make himself unavailable for decisions on rulership while having campaigns carried out elsewhere.
Because Augustus hardly did any of the campaigning-he was just there, while Agrippa actually ran the show in every instance.
3) No, because these empires were built by men with actual long term vision, not "Man, this is boring, I'm going to conquer Arabia."
Picture for a second Augustus dying at 33. Now at 33 (30 BC), he had just finished a lifetime of constant military campaigning (led and operated by Agrippa), and showed no intention of actually thinking about a long term plan for how he was going to rule the empire. Instead, he was planning more campaigns: a possible invasion of Britain, a subjugation of the Danube provinces, an invasion of Germania, an invasion of Arabia, and he may have even been contemplating an attack on the Parthian Empire. In fact, for the next 7 years, he shows no inclination to moving towards a durable way of managing the state, other than constantly being consul each year. It was no coincidence that it was after he recovered from a near mortal sickness that he sprung into action to create a longterm solution, which we know as the Principate.
Now why do we have to assume Alexander had no intention of creating an efficient and effective method of governance for his empire, especially when he was already showing signs of moving in that direction at least (unlike Augustus)?
Succession alone does not help - Alexander with many children is likely to run into the problem that has bedeviled the Macedonian kingdom for the past two centuries, because there's no basis to say "This child succeeds, the others just have to suck it up." that can be relied on.
As Velasco pointed out, he would almost surely use the Persian method of succession.
So why is it the first time he could put any focus on it?
Why did he choose to spend his adult life to date campaigning?
Alexander could have stopped in Asia Minor. He could have stopped in Mesopotamia. He could have stopped in the Levant. He could have stopped in Egypt.
But nooooo, Alexander wanted more. So of course he's not going to have any time when he's using every waking moment to campaign. That's the frickin' problem man.
His goal from the start was to conquer, and in a sense, become the ruler of, the Persian Empire. That's why he didn't stop there. That's why his death at that time is so frustrating for someone trying to predict how he'd rule from then on out, because he had just finishing subjugating and conquering the whole of the Persian Empire. Now that the Persian Empire was conquered, he doesn't need to spend every moment on campaign. In fact, it may be unlikely that he would play any major role in his Arabian campaign to begin with-his doctors were almost adamant that he should not strain his body (i.e. go on difficult campaigning) given his wound from the arrow through his throat.
Or he could ignore it, and leave Antipater as regent-like I said, there's precedent for that decision, considering he did the same thing when he left Macedon.