"where are the pre-flood advanced life forms including humans?"
I reject the premise of your question. Trilobites were advanced. They had eyes, which means a highly developed nervous system. They matured by molting, which is a highly complex mechanism.
As for humans and other "complex mammals", they would be more likely to find higher ground, cling to debris, etc., which would have left their bodies open to exposure and decay instead of fossilization. In addition, the human population at the time of the flood is estimated to be small enough that it would be unlikely to ever find a human fossil even if all humans at that time were fossilized. Most humans and complex mammals are found in post-flood sediments. However, human artifacts have been found in much lower strata.
"How did the dinosaurs arise AND vanish entirely during the flood?"
They didn't arise _during_ the flood. They arose before it. They also didn't die out in the flood. While they have mostly died out by now, history is replete with encounters with dinosaurs. Pteradactyls were a fairly common sighting in Europe up until about 2 centuries ago. John of Damascus wrote about the biology of dinosaurs as well as an encounter with them that the Roman army had (I don't know all of the details as I don't read Latin, and there is no translation available). There are a few Saurapod dinosaurs presumed to be alive today in some parts of the Congo. They wouldn't be the first species presumed to be dead for tens or hundreds of millions of years that turned up alive somewhere.
"How did the birds and mammals apparently arise and change considerably in appearance during the flood itself?"
I'm not very familiar with birds, but mammals are mostly absent from flood sediments, except for small mammals. Post-flood, creationists are in general agreement with the changes postulated by evolutionists. Creationists actually think that change occurs faster than evolutionists. However, the change is limitted according to the semantics of the animal's plan (both genetic and epigenetic). Therefore, it can go longer distances in a single bound, but it has stricter boundaries than those presumed by evolutionists.
However, a lot of the documented changes by evolutionists are done by a selective analysis of the evidence. This is especially true in human ancestry analysis. For a discussion of this, see:
http://www.answersingenesis.org/creation/v15/i2/fossils.asp
A summary view of all this can be found here:
http://www.answersingenesis.org/docs2/4419.asp
It is true that there are many unanswered questions, but that is entirely the point of the creationist scientific persuit.
I am not using "advanced" in the sense of "multicellular" or even "vertebrate." You are advancing a model in which various life forms including humans and birds (see the Book of Genesis for a more complete list) existed for a thousand years before the flood and suffered most of their numbers to be destroyed in the flood, whose sediments are somehow mistaken to for the residues of about half a billion years of Earth's geology but are actually the result of one flood in one year. At one point a few posts ago, I got that wrong and said the flood starts at the P-T boundary, but that's not your claim. You have the flood starting at the Precambrian-Cambrian boundary which is even earlier and sillier.
Your model clearly predicts pre-flood humans. But there aren't even any pre-flood rabbits. I predicted your behavior on this point when I mentioned that YECs answer the questions they can't answer by pretending there is no such question.
You are peddling an inferior product here. There is no need to ignore away questions for which we already have answers that make sense.
As for humans and other "complex mammals", they would be more likely to find higher ground, cling to debris, etc., which would have left their bodies open to exposure and decay instead of fossilization.
Nobody got buried even after the entire Earth was covered? Where exactly was this higher ground? Your answer is downright heretical. Yer prolly goin' ta hay-ull fer thet, bo-ah!
You are ignoring the actual content of the fossil record in every matter. The fossil record shows dinosaurs arising in the Triassic, evolving a rather different set of forms by the Jurassic, evolving another set of forms by the late Cretaceous, and nothing but their descendant birds after the K-T boundary. There are any number of distinct layers which should not be there in a one year flood, any number of appearances and extinctions which should not be there in a one-year flood.
Former YEC (and oil geologist) Glenn R. Morton has analyzed problems with flood geology. I'll give a little sample here.
Too many fossils for one flood.
Then there's this detailed list by Ken Harding. Lots of items in that one.
Have a ball.
The above is your answer. Below is the problem.
Where are the humans? Where are the lizards? Where are the amphibians? Are they clinging to wreckage?
WHERE ARE THE FISH?
Do the rock strata represent eons of time? There is a wealth of evidence that the rock strata do not represent vast periods of time. For example, the huge Coconino sandstone formation in the Grand Canyon is about 100 m thick and extends to some 250,000 km2 in area. The large-scale cross-bedding shows that it was all laid down in deep, fast-flowing water in a matter of days.Just wrong. It's full of fossilized surfaces bearing fossil tracks, and raindrop imprints. It's desert sandstone that took a long time to accumulate.
http://www.talkorigins.org/indexcc/CC/CC365.html.
What few flimsy items they cite for this do not fill the bill. Some (unmineralized dinosaur bone) aren't even true.Evidence that dinosaurs and humans co-existed
"Plenty" exist, and even evolutionists cite them. But there wasn't room for AiG to cite any, and evolutionists obviously aren't worried. The example buried in the footnote, "Precambrian" pollen, doesn't bear up under examination.Out-of-sequence fossils