When we install express deployment using Web Platform Installer, it automatically configures all required Windows Server Roles & Features. However, in development environment where we want to build new WAPack virtual machine, it is always better to build the baseline image with all required roles and features.

You can find a reference server configuration file that I generated at Technet Gallery. You can use the following PowerShell scripts to configure server with the pre-requisites.

Using this approach brings down the configuration by Web PI from 53 components to 36 for WAPack UR4.

# If you want to generate the configuration based on an existing WAPack Server
# Get-WindowsFeature | 
#       ? { $_.Installed -AND $_.SubFeatures.Count -eq 0 } | 
#       Export-Clixml C:\WAPack_ServerRolesAndFeatures.xml

$serverFeatures = Import-Clixml C:\WAPack_ServerRolesAndFeatures.xml 
foreach ($feature in $serverFeatures) { `
    Install-WindowsFeature -Name $feature.name `
}

You can find software requirements for Windows Azure Pack express deployment here.