Basic question about using PowerShell to modify user assignments in SSRS - powershell

Question

I have somple experience in PowerShell but I don't have experience in using it to automate SQL Server Reporting Service. Basically I want to assign a user a role to a particular report object in SSRS. I have found the following codes in
SSRS: How to assign multiple users a role to a report quickly?
It seems a good start for creating my script.
function Add-SSRSUserRole
(
[string]$reportServerUrl,[string]$userGroup,[string]$requiredRole,[string]$folder,[bool]$inheritFromParent
)
{
#Ensure we stop on errors
$ErrorActionPreference = "Stop";
#Connect to the SSRS webservice
$ssrs = New-WebServiceProxy -Uri "$reportServerUrl" -UseDefaultCredential;
$namespace = $ssrs.GetType().Namespace;
$changesMade = $false;
#Look for a matching policy
$policies = $ssrs.GetPolicies($folder, [ref]$inheritFromParent);
if ($policies.GroupUserName -contains $userGroup)
{
Write-Host "User/Group already exists. Using existing policy.";
$policy = $policies | where {$_.GroupUserName -eq $userGroup} | Select -First 1 ;
}
else
{
#A policy for the User/Group needs to be created
Write-Host "User/Group was not found. Creating new policy.";
$policy = New-Object -TypeName ($namespace + '.Policy');
$policy.GroupUserName = $userGroup;
$policy.Roles = #();
$policies += $policy;
$changesMade = $true;
}
#Now we have the policy, look for a matching role
$roles = $policy.Roles;
if (($roles.Name -contains $requiredRole) -eq $false)
{
#A role for the policy needs to added
Write-Host "Policy doesn't contain specified role. Adding.";
$role = New-Object -TypeName ($namespace + '.Role');
$role.Name = $requiredRole;
$policy.Roles += $role;
$changesMade = $true;
}
else
{
Write-Host "Policy already contains specified role. No changes required.";
}
#If changes were made...
if ($changesMade)
{
#...save them to SSRS
Write-Host "Saving changes to SSRS.";
$ssrs.SetPolicies($folder, $policies);
}
Write-Host "Complete.";
}
[string]$url = "http://localhost/ReportServer/ReportService2006.asmx?wsdl";
Add-SSRSUserRole $url "Everyone" "Browser" "/MyReportFolder" $true;
Add-SSRSUserRole $url "Domain\User" "Browser" "/MyReportFolder" $true;
Now I have two elementary questions:
Do I need any SSRS modules to be installed in my PowerShell in order to run the above script?
The sample code above assign a permission to a folder. What changes are required if I want to assign permissions to a report object directly instead?
Thanks for your response in advance,