$i and $web aren't special variables. They are just popular names that people reuse. The name of the current object in a foreach-loop is defined by you.

Ex:

#Creating a simple array for the demonstration
$MyArrayOfAwesomeObjects = 1,2,3

foreach ($ThisVariableIsAwesome in $MyArrayOfAwesomeObjects) {

    #Here, $ThisVariableIsAwesome is the current object, and we can call methods on it.
    $ThisVariableIsAwesome.GetType()

}

IsPublic IsSerial Name  BaseType
-------- -------- ----  --------
True     True     Int32 System.ValueType
True     True     Int32 System.ValueType
True     True     Int32 System.ValueType

As for % -> Foreach-Object, that is just an alias. You can view all aliases with Get-Alias

ls variable:* should work, or Get-Variable. If these are resulting in bad output, it's due to a poorly-implemented host, not with powershell itself. If you open the standard console host (run powershell.exe), you will see that these work fine.

If you need to work around a bad host, you might have better luck dumping everything to explicit strings:

Get-Variable | Out-String

or

Get-Variable |%{ "Name : {0}`r`nValue: {1}`r`n" -f $_.Name,$_.Value }