Question one: I've heard that Dawkins covers things like eyes existing, etc., in the Blind Watchmaker, comparing it with the Watchmaker argument. Okay, I'm cool with that. I can see Eyes gradually appearing and increasing in usefulness over time. Maybe it starts out you can tell day vs. night, then can pick up shadows of motion, etc., etc.. The problem I have is when you have an evolved trait that's actually a HINDRANCE until it reaches a certain point.
This is one of the better objections to evolution out there. Frankly, I'm surprised that it isnt used by anti-evolution advocates out there. The truth is we aren't really aware of systems like this.
Take birds and their wings (not to mention hollow bones) for an example. How does that start out? Maybe extra flaps of skin, which just get in the way?
Doesn't get in the way. Can have at least two purposes 1) heat regulation 2) gliding or increasing jump length. Note that so called flying squirrels do exactly this and different forms of flying squirrels have different degrees of such skin, all the way from flaps that are small enough that you wouldn't notice them at first glance to huge scary things attached to their arms.
A skeletal structure more susceptable to breaking, and one that doesn't knit as well, due to hollow tubes for bones? I would think that any creature that started down this evolutionary path, would actually reproduce LESS until if and when it finally hit that point where it was capable of gliding and/or flight.
Hollow bones aren't as bad as you make out. Even if you are on the ground hollow bones can be useful if you need to be fast. They also take less calcium to produce. Hollow bones are a problem if you were in species like say a human or a wolf which needed to survive many violent encounters but it isn't as much of an issue otherwise. Hollow bones can be quite strong. And there's some reason to believe that the bones of birds got more hollow as birds became more flight oriented. Archaeopteryx for example has hollow bones but the evidence (as I understand it. I haven't studied bird evolution in detail) suggests that they are less hollow than that of the modern bird.
How does evolution account for these "one step back for two steps forward" changes? Shouldn't each change generally result in immediate benefit, or else the creature would be passed up by its more (immediately) better-adapted cousins?
Yes. See above.
Question two: The frailties of humans compared with other animals. Let's say we evolved from creatures that were not as smart as us, but had other useful physical traits to compensate for it. Thicker hides, more muscle mass, etc.. Over time we've lost these traits, presumably because they're no longer necessary; our ability to use tools has replaced it. But the thing I don't get is, just because they aren't NEEDED, doesn't mean they aren't USEFUL.
Well, usefulness doesn't mean you have high selection pressure. Also having thicker hides, more muscle mass etc. means that you have fewer resources going to the brain and other things that humans have that are well-developed. The niche for humans is that a) we are really smart and b) we are really flexible. We aren't the fastest species, we're not the strongest, we're not the best swimmer but we're pretty fast runners, pretty strong, and pretty good swimmers. Humans are sort of the jack-of-all-beneficial-traits and then we get brain power on as gravy.
Hypothetical situation: Let's say we have two tribes of proto-humans: both of which are intelligent, can use tools, etc., but one is PHYSICALLY more like apes (muscles, hide, etc.), while the other looks like us. Assuming all other factors being equal, wouldn't the ape-like tribe be more successful?
Not necessarily. If you are more ape like that means you need to consume more protein and you aren't going to be as smart. You are correct that if you had humans who were just like normal humans but stronger that they would likely outcompete the standard human. But that sort of thing rarely occurs in nature. There's some evidence that something like this happened with Neanderthals. They may have been slightly less bright or even at the same intelligence level but caloric consumption and other issues made them lose even though they were physically stronger than modern humans. Remember, food resources for most of human history were scarce.Edit:Formatting