Is the installation of Xcode from App Store enough for having the developer tools?
Installing Xcode 4.3 does install the developer tools, but not for command line access. With this version, everything has been moved into the application bundle, which means there is no need for a uninstaller, since you can just delete the application. If you want to install the command line tools, open Xcode and go to Xcode > Preferences > Downloads, select the Components tab, and click the button next to Command Line Tools. (This might add an uninstaller somewhere, but I'm not sure.)

As for Homebrew, you might have to wait for an update before it supports Xcode 4.3, since everything was moved. I would suggest trying /Applications/Xcode.app as the &lt;xcode_folder_path&gt;, since most of the hierarchy appears to be the same.

The homebrew developers are tracking these changes in their bug database so, you may want to monitor this thread for workarounds and notification of when the homebrew system will effortlessly work with the new changes for Xcode 4.3.