Using PowerShell to import CSV data from Vendor database to manipulate Active Directory Users

Question

Hello,
I have a big project I am trying to automate.  I am working in a K-12 public education IT Dept. and have been tasked with importing data that has been exported from a vendor database via .csv file into Active Directory to manage student accounts. 
My client wants to use this data to make bulk changes  to student user accounts in AD such as moving accounts from one OU to another, modifying account attributes based on State ID, lunchroom ID, School, Grade, etc. and adding new accounts / disabling
accounts for students no longer enrolled.
The .csv that is exported doesn't have headers that match up with what is needed for importing in AD, so those have to be modified in this process, or set as variables to get the correct info into the correct attributes in AD or else this whole project is
a bust.  He is tired of manually manipulating the .csv data and trying to get it onto AD with few or no errors, hence the reason it has been passed off to me.
Since this information changes practically daily, I need a way to automate user management by accomplishing the following on a scheduled basis.
Process must:
Check to see if Student Number already exists
If yes, then modify account
Update {School Name}, {Site Code}, {School Number}, {Grade Level} (Variables)
Add correct group memberships (School / Grade Specific)
Move account to correct OU (OU={Grade},OU=Students,OU=Users,OU={SiteCode},DC=Domain,DC=net)
Remove incorrect group memberships (School / Grade Specific)
Set account status (enabled / disabled)
If no, create account
Import Student #
Import CNP #
Import Student name
Extract First and Middle initial
If duplicate name exists
Create log entry for review
Import School, School Number, Grade Level
Add to correct Group memberships (School / Grade Specific)
Set correct OU (OU={Grade},OU=Students,OU=Users,OU={SiteCode},DC=Domain,DC=net)
Set account Status
I am not familiar with Powershell, but have researched enough to know that it will be the best option for this project.  I have seen some partial solutions in VB, but I am more of an infrastructure person instead of scripting / software development. 
I have just started creating a script and already have hit a snag.  Maybe one of you could help.
#Connect to Active Directory
Import-Module ActiveDirectory
# Import iNOW user information
$Users = import-csv C:\ADUpdate\INOW_export.csv
#Check to see if the account already exists in AD
ForEach ( $user in $users )
#Assign the content to variables
$Attr_employeeID = $users."Student Number"
$Attr_givenName = $users."First Name"
$Attr_middleName = $users."Middle Name"
$Attr_sn = $users."Last Name"
$Attr_postaldeliveryOfficeName = $users.School
$Attr_company = $users."School Number"
$Attr_department = $users."Grade Level"
$Attr_cn = $Attr_givenName.Substring(0,1) + $Attr_middleName.Substring(0,1) + $Attr_sn
IF (Get-ADUser $Attr_cn)
{Write-Host $Attr_cn already exists in Active Directory

Answer 1

Thank you for helping me with that before it became an issue later on, however, even when modified to be $Attr_sAMAaccountName i still get errors.
#Connect to Active Directory
Import-Module ActiveDirectory
# Import iNOW user information
$Users = import-csv D:\ADUpdate\Data\INOW_export.csv
#Check to see if the account already exists in AD
ForEach ( $user in $users )
#Assign the content to variables
$Attr_employeeID = $users."Student Number"
$Attr_givenName = $users."First Name"
$Attr_middleName = $users."Middle Name"
$Attr_sn = $users."Last Name"
$Attr_postaldeliveryOfficeName = $users.School
$Attr_company = $users."School Number"
$Attr_department = $users."Grade Level"
$Attr_sAMAccountName = $Attr_givenName.Substring(0,1) + $Attr_middleName.Substring(0,1) + $Attr_sn
IF (Get-ADUser $Attr_sAMAccountName)
{Write-Host $Attr_sAMAccountName already exists in Active Directory
PS C:\Windows\system32> D:\ADUpdate\Scripts\INOW-AD.ps1
Get-ADUser : Cannot convert 'System.Object[]' to the type 'Microsoft.ActiveDirectory.Management.ADUser'
required by parameter 'Identity'. Specified method is not supported.
At D:\ADUpdate\Scripts\INOW-AD.ps1:28 char:28
+ IF (Get-ADUser $Attr_sAMAccountName)
+ ~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidArgument: (:) [Get-ADUser], ParameterBindingException
+ FullyQualifiedErrorId : CannotConvertArgument,Microsoft.ActiveDirectory.Management.Commands.GetAD
User