Who has access through VPN?

Just curious what criteria anyone has for allowing access to your church network drives through a VPN connection from a home computer. Currently we have very few staff who need access after hours from home. I am trying to establish standards for determining who can access network drives from home? Do you allow any volunteers to have access from home? How to you make sure your VPN users' home PCs are sufficiently up to date to protect against the nasties that abound on the internet? Any feedback you provide will be much appreciated!