Handy Links when Planning Azure IaaS
Azure Subscription and Service Limits, Quotas, and Constraints
http://azure.microsoft.com/en-gb/documentation/articles/azure-subscription-service-limits
About VPN Devices for Virtual Network
http://msdn.microsoft.com/en-us/library/azure/jj156075.aspx
About Network Security Groups:
http://msdn.microsoft.com/en-us/library/azure/dn848316.aspx
Network Security Groups:
http://azure.microsoft.com/blog/2014/11/04/network-security-groups/
Resource Groups
http://azure.microsoft.com/en-gb/documentation/articles/azure-preview-portal-using-resource-groups/
Using Resource Groups with PowerShell
http://azure.microsoft.com/en-gb/documentation/articles/powershell-azure-resource-manager/