For example is it possible to diagram an evolutionary change, including everything that must be in place, or take place, for even a small change to occur?
What do you mean "small change"?
There is a form of dwarfism that is caused by a single point mutation in a single gene that causes an amino acid change in a single protein. Yet that single change results in disproportionate limb growth, alterations in the facial skeleton, reduction in interphalangeal joints, etc.
This means that all of the bones, all of the nerves, all of the blood vessels, etc. in each limb were all affected by that one change.
I mention this for on another forum some years ago, a creationist claiming to be well read and to have 'studied' the issues claimed that for even a tiny change in one limb we would need to explain all of the mutations "needed" to change all of these things individually.
Which means that he, like I assume you, does not understand how development (or the underlying genetics) works.
I saw a semi-professional creationist computer expert insist that it must have taken at least 1 million beneficial mutations to alter just the pelvis of a quadrupedal chimp-like ancestor to a fully bidepal pelvis of a human. And, like you, when asked for his rationale he said it just had to be, for he could not understand any other way. And he, like you, was totally unable to provide any evidence whatsoever regarding the number of such mutations that phenotypic changes would "require."
In fact, this is a very common mantra among creationists, especially those with backgrounds in engineering of some sort.
Ever heard of Walter ReMine? He wrote a book in the 1990s in which he took an outdated equation based on information understood in the 1950s (known as 'Haldane's dilemma'), applied it to human evolution, concluded that since the estimated divergence of chimps and humans, a maximum of 1667 fixed, beneficial mutations could have accumulated in our lineage, and darn it, that was just not enough.
How did he know it was not enough? He just did - 'common sense', and besides, he was an electrical engineer, so...
He, like most creationists, also got caught misrepresenting one of the people he interviewed for his book (George Williams), whom he presented as agreeing that 'Haldane's dilemma' was a big problem for evolution despite the fact that Williams was of the opinion that there was no dilemma at all since Haldane has made errors in his calculations.
Anyway...
Since these small changes (perhaps down to the molecular level) are the basis of evolution, is there a comprehensive explanation for them?
A comprehensive explanation for mutations? Um.... Yes? Replication errors? They have been sort of measured and everything...
It just seems that evolution is a sudden inexplicable (and almost always fortuitous) change that must include thousands of other minute changes to accomplish.
I'm sure it seems that way to you, but you have, afterall, admitted that you don't understand it, so...
It's like a switch gets tripped and thousands of biological processes 'cascade' into action resulting in a successful change, like an intricate setup of thousands of dominos falling in order when the first one is tripped.
Amazingly, that is sort of how development works! The thing that folks like you cannot seem to grasp is that we only see the "end products" that worked - if that 'cascade' ends up producing a non-functional heart as a by-product, for example, the embryo dies very early on and we know nothing of it.
Depending on the source you read, this in fact occurs ALL the time as some 40-60% of all fertilized eggs dies, often well before the woman even realizes that fertilization has taken place.
Multiply this event by the uncountable trillions that must successfully occur over time in order to produce the global biosphere/ecosystem that we see today, all from a simple microscopic organism.
See above.
it really does help to dump the strawman versions of things.
It would be even better if creationists could turn some of their 'skepticism' towards their own "beliefs" now and then. But that never seems to happen for some reason.