I am sorry, But you call your self a power user/Developer? you sir. make me laugh!
secondary click can be enabled in preferences. the scroll is still there, you can still scroll with the mouse.
pageup/down still exists, Hold FN+arrow keys
as for finder, all the stuff you say you miss is still there. Only a right click away.
the scrollbar that disappears free some windows space. when you scroll with your mouse / trackpad what ever it will show up, it even shows up if you are using arrow keys to scroll.
One window apps like Xcode, uhm as far I can remember, Xcode has always been a one window app?, fullscreen mode, some finds it useful to avoid distractions and since interface builder is now a part of Xcode you don't have to exit it. but lets be honest, you don't have to use it if you don't like it, its just an option
If you had taken your time to read change logs from Xcode updates you would have notices that they bundles stuff in the new app.. jesus.
Mac isnt dumped down, it has just evolved, the only thing that is dumped down is the damn exposé which i miss greatly, but as a developer I adapt or end like an old dinosaur. IF you are an developer YOU of all people should know this.
So if you actually took your time to investigate how things work in 10.7 I don't say that it is a great OS, But I embrace change and adapt to it, rather than rant over things that wont change, I develop new workflows based on the tools given to me. You would have noticed all these things.