Alien Civilization, Another Perspective (By Michelle Wong)

1)Energy requirement. I think as for the energy harvesting point of view, let's may be assuming it in this way. Driving your car to Singapore will take 3 full tanks of petrol. So since you can't drive all the way to Singapore with 1 full tank, you would have at least stop twice to refill. Then, can the same analogy can be applied here?
And the second suggestion would be that we need a lot of petrol/coal/natural gas or whatever energy supplier to generate 10^13 Watt because these listed supplier above is producing only so much energy per unit mass. But what if the alien is using different material which generate 10 millions time of energy for the same unit mass? That planet might not be the exactly the same planet as we have now, not only in terms of composition of matter but could be also the different matters (and I wonder is the chemistry periodic table is fixed and no more additions or expansions?).
2) The mindset of alien civilization. This is very interesting to actually think it in hypothetical way, if I am about to dream of the Utopian society :P But putting that aside, I would have to ask myself the few obvious question. What is their motivation to explore the universe? The reason I ask myself this question is that since you suggested that a LOT of energy is required, they must be looking for something before investing such enormous amount of energy! (of course, we presume that They think humanly like us *cost-benefit analysis*, which might not be true as I will ask later). Since you had proposed that it could be due to escape from genocide/warring/conflict, should we be worried about if our planet is habitable to them, or they will just pass by? :P
I read this somewhere about the question: if 2 different species of animal meeting up together for the first time in their lives, for example like Galapagos tortoise vs Orang Utan, what would be the reaction. They said that the observation made often than not is actually neutralism, instead of jumping straight to fighting. Of course, they said it based on evolutionary psychology (I think it is in George Miller's The Mating Mind). Now, the trick question is, will human-alien relationship be something like neutralism or fighting over reproduction/survivality?
Another interesting point: what makes these aliens so great in producing such advanced technology to be able to travelled to this space. We might think they must have such high intelligence, philosophical undertakings (if they manage to be so peaceful and have no conflict at all), or supreme collectivist mindset (you know, just be collective, like the ants in the hive), and so on. But take a step backward: put yourself into the ant shoes and have a look at human being. If you look at human from the eyes of ant, you would be wondering what makes them travel so fast, or you as a fish, wow, human being actually floating on the water at one moment and sinking into water next and so forth. At the end, actually we are comparing it in a very different realms: one being ant/fish, and another one would be human being. Why I brought this up? I would think that if there is any alien to be met in the future, let's not presume too much on why or how they become where they are from the very human perspective, i think some call this anthropomorphism.
And coming to your last point: how good we could reconcile with others in ensuring our survivality, i think a lot of philosophers/great thinkers have expounded heavily on this subject by understanding human nature and the prospects of it. There is only 2 points coming to me at this moment: Hegel said "What experience and history teach is this — that nations and governments have never learned anything from history, or acted upon any lessons they might have drawn from it." and resources will become scarcer and rarer, and may be we are bound for collision, 2 persons wanting the same thing. But what resources or at what rate, I have no idea ;)