I drag documents into the dock to open them with a specific application. There are a lot of document types that I deal with where there’s no one-size-fits-all default—stuff like media files especially.

I'm not trying to talk you out of any criticisms of the OS, but just FYI: you can drag files onto app icons in cmd-tab, too. Start dragging, hit cmd-tab, and then hold cmd. The app icons hang around until you release cmd, and you can drop files on them.

I use this all the time to handle things like text, images, pdf etc to open them in non-default apps. I find this a lot easier than dealing with the dock. Hope this helps!

If you want to have two windows side by side, each maximized to half the screen, how would you do it with Expose?

clicking in dock is way easier than doing cmd-tab because cmd tab order keep changing . In dock we can easily discover the app as they don't move around.

I think Cmd-Tab is really bad if you end up using lot of apps. Alfred is way better for such purpose imo.

How do you use Alfred to replace cmd-tab?

You can sort of use Alfred as an app switcher - by entering the name of the app you want to switch to. The first letter is usually enough (e.g. to switch to Chrome, invoke Alfred, hit C, hit Enter). If you have to cmd-tab through many open apps, using Alfred can be faster.