The only reason why part of it is the same is that both the sciences and mathematics tries to gain insight and understanding. I doubt you could find a single academic discipline that doesn't share the properties you mentioned. This is just the way humans gain understanding; by experimenting with concrete objects, by trial and error, and by building on previous results. So all pursuits to gain understanding of something will include these elements.
I agree, there is a unity in the method.
If you really took the analogy seriously, then math would be extremely bad science because it doesn't keep re-evaluating its hypotheses. The main difference between math and the other sciences is that in the other sciences you can never be sure about the truth of a theory so you keep re-examining it and trying it in new contexts. In math you try it with maybe a few objects, you then prove it to hold in general, and then you don't need to re-examine the truth of the statement.
Here I disagree, mathematics does re-evaluate its content (hypotheses is a tricky word: what is an hypotheses in Mathematics? The statement of a theorem, the validity of the logical steps in the proof(s), the nature or accepted definition of the concepts involved? There are several possibilities). This happens when someone proposes a new proof that is judged to be more rigorous than the ones before (even "rigour" is a complex concept, that evolves with time); for example, there proofs in Euclid that are still deemed rigorous today, but Analysis and Topology, for example, only attained a "rigorous" status well into the XXth century; granted that they appeared much later, but the concept, say, "function" is still evolving.
In the Natural Sciences (I don't like the name; I'm just using it to distinguish them from Mathematics), there are indeed theories that are revised (and even abandoned) when the range of empirical data widens and falsifies them. This is not so evident in Mathematics, but happens, for example, in the calls of the constructivist schools to take a more critical approach to the validity of the logical steps, or the proper format of proofs; the mais difference is that, in the NS, eventually everyone is forced to accept the evidence, while in Mathematics this is more subtle; one extreme example is Brouwer's model of the real continuum: almost nobody uses is, not because there is something intrinsically wrong with (in fact, its consistent iff the classical model is), but because there is no compelling reason (comparable to the pressure of evidence) to overhaul a quite large part of Mathematics in favour of the other.
Regarding truth, it's not a mathematical concept (but I believe that it's an objective one; I'm no relativist), but a metaphysical one, and we do not have a really good formal theory of it; it's perfectly possible that the truth of some statements, even mathematical ones, must be revised in the future. Other recent questions are the rise of experimental mathematics and the possible limitations to our hability of to prove some statements implied by Complexity Theory.
It refers to results in modern philosophy and logic that I do not understand.
This article is not very good. What parts are you referring to? The ones referring to 1930's are the failure of Frege and Russell's project to reduce Mathematics to Logic (I'm
not talking about Gödel's Incompletness Theorems, please don't drag them here; they are not relevant to this). This reduction is currently being investigated again, with some surprising results: it seems that we need veru little beyond Logic to reconstruct most Mathematics.