Would all possible intelligent species tend towards the same moral and ethical precepts that humans do? Or would species with radically different biologies, brain structures, mating patterns, etc. tend towards equally different moral precepts and ethical concerns?

This is a wonderful question, which goes to the heart of just what ethics is about. Some philosophers--such as Immannuel Kant--have maintained that ethics consists in universal principles of practical reason, which must therefore apply to all rational beings, including God, angels, devils, and any other rational being whatsoever. This 'universalist' conception of ethics obviously abstracts away from any other differences among beings to identify rationality and the capacity to be bound by ethical obligations. If, however, one thinks that ethics is about how agents negotiate their relations with one another, how they, as it were, 'get along', then it would seem that the sorts of differences that you point out would be relevant to shaping the ethical relations of these beings, and consequently, differences in biology, etc., might well lead to different ethical concerns. So what is ethics about? Is it about duties that apply to all rational beings? Or is it about how beings negotiate their...

According to Kant, as I understand him, nature has an orderliness that appears (or compels belief in) to have been ordered by a divine power, but that the validity of such an appearance can neither be proved or disproved by the power of (pure) reason. Darwin's theory shows (as I understand it) that all life is the product of successive random forces. Does Kant's philosophy remain unaffected by this Darwinian insight?

You're quite right about Kant. The purposiveness--orderliness--of organisms in particular and, indeed, of nature in general, while manifest in experience, cannot themselves, according to Kant, be proven from experience. In the Critique of Judgment (henceforth referred to as 'KU' and cited from James Creed Meredith's translation, revised by Nicholas Walker [Oxford University Press, 2007]), Kant explains that the principle of the intrinsic purposiveness of organisms "must be derived from experience....But owing to the universality and necessity which that principle predicates of such purposiveness, it cannot rest on merely empirical grounds, but must have some underlying a priori principle" (§ 66). Since, however, according to Kant, and in accordance with Kant's understanding of Newtonianism, nature itself is merely a realm of efficient causes, there is no room in nature for purposiveness (KU § 66), which leads to an antinomy of teleological judgment (KU §§. 69-78, esp. §§. 69-71), very roughly...