As you say, suicide, although not encouraged, is still not a sin or viewed negatively to the degree at which it is in other religions, particularly the Abhramic ones. However, it is still possible, under certain circumstances, for one to suffer and yet experience enlightenment.
Godhika is prominent for he was a very devoted monk of 'advanced level' and came close to achieving enlightenment, but his body was deteriorating much faster and thus pain did not let him proceed with his mediation. After Godhikka murdered himself, Siddhartha Buddha arrived at the scene and proclaimed he had attained Nibbana, nevertheless. No subsequent incarnations of Godhikka took place, according to sources.
Did you try googling a combination of "buddhism", "suicide" and "godhika"? I do have the links below:
http://www.urbandharma.org/udharma/suicide.html
http://www.palikanon.com/english/pal...godhika_th.htm
http://suttanta.tripod.com/khuddhaka...da/dha043.html
There is also a similar case of Chana:
http://tipitaka.wikia.com/wiki/Channovada_Sutta
So, this may put one in doubt how true is enlightenment and all the practices that lead to it. On the other hand, it may only validate otherwise that, in one's quest for enlightenment, body really weights nothing, which again strengthens all the initial points in Buddhism.
I do agree that the very fact that we are right now in the human form of reincarnation gives us more room for improvement and development compared to other, lower forms. Besides, among them, human is the one that gives us the most empowerment over decisions that will directly or indirectly affect the rest of beings and disposition of events.
And, then again, it is very rarely when one is reborn in a fully positive human life and the other - in the fully negative. More than often the case is of mixed nature. And, as may be experienced by most of us at least once in a while, good things don't happen without bad ones. A day may encompass so much positive and negative together that it could serve as a synecdoche to entire lifetime.
It can also be that one would be born in the negative circumstances, but later progress to impove his conditions. In this case, I would like to ask if there is a concept of fate or destiny or anything else related to it in Buddhism?
And, if there is no notion of soul in Buddhism, what is it that we describe our own selves that undergo numerous live forms in the quest for ultimate enlightenment?
Lastly, I do remember reading, although that was a while ago, that in Hinduism there are three states of mind that, in the context of karma, may predominate in one's life. Upon these three states, it can be judged whether a person may experience the results of his actions (karma) immediately and within short period of time, or later after years, or even only in the subsequent lives. The first would enjoy the most of karma, as it will quickly teach and direct him/her to understanding the consequences of his actions and learn to improve upon recognizing the patterns of good and bag behavior-experience. The other two are less desirable, but more common, when a person does wrong, but bears consequences only later in his/her life or not even until the next life. Does a similar idea exist within the framework of Buddhism? And, if not, does it mean that karma that happens to one immediately has no difference from the karma that takes place only in next life form? I believe all this matters, because, in the end, it is time that teaches one and the shorter it takes for bad karma to realize itself, the faster will one begin questioning self and start learning from his mistakes. This is rather analogous to any lab experiment that tests one's behavior and defines what procedures in what time frame are necessary to invoke the desired response in the subject.
So, as I understand, it is normal for one to be putting his enlightenment before all the rest in doing good to others, if he/she is only in the beggining stage of training self's behavior? And, so naturally this training may grow to become a natural attitude and likewise the person's ultimate goal will also become to serve others. Do I get it all right?
Well, we can say that, in our current and previous, lower life forms, suffering, especially in its perhaps extreme forms, not only happens to our physical bodies, but also to our inner pains and unpleasant personal experiences. According to the Buddhist teachings, do we also carry these along to the realm of enlightenment? Or, we fully abandon everything that is of this world and let ourselves be free, including from our memories of the lives we have had? Can one downgrade from the enlightenment realm back to lower life form, if he/she overindulges in these pleasures? Or, this is no more a case?