Lync Online PowerShell issues and solutions

So, I was asked to implement the fixes documented in Christian Burke's blog entry, SOLVED: Online Meeting Icon Missing from OWA in Exchange Online - which is a fairly complex and PowerShell heavy blog - he makes use of Lync Online PowerShell, Lync On premises PowerShell, and MSOL PowerShell(Microsoft Online Azure PowerShell)

I didn't think it would be, but the most complex part of completing the tasks on that blog was getting me connected to our Lync Online PowerShell!

Issue #1 - when running the New-CsOnlineSession, you are prompted for a TargetServer
You installed Lync on premise tools since you installed Lync Online.   Uninstall and reinstall the Lync Online Powershell.  See KB2955287.

Issue #2 - when running New-CsOnlineSession, you are getting "Unable to discover Powershell endpoing URI"  (Yes, the error has endpoint spelled incorrectly)

Your Lync autodiscover record is either pointed to on premise or non-existant.  If it is pointed to your on premise, you need to use -OverrideAdminDomain and specify your tenant domain.

Issue #3 - when running New-CsOnlineSession, you are getting errors like "Get-CsWebTicket : Arithmetic operation resulted in an overflow." or "Get-CsWebTicket : Failed to logon with given credentials" when you know your credentials are correct.

This one took a while.  I had MFA enabled and enforced on my account.  Apparently this will prevent me from using PowerShell.  Workaround is to utilize app passwords, or disable MFA to connect to PowerShell.  
4/20/2015 Update:  App Passwords worked for a very short window for this purpose.  Accounts with MFA enabled will need MFA disabled to use PowerShell

More on App Passwords in my next article "Azure AD, Multi Factor Authentication and App Passwords"

I'll post up any more as I find them, but these three hopefully will help some of you!
Chris