We need a Proxy Server (TMG?) for the external web access

[leonarwo]

https://technet.microsoft.com/en-us/library/mt346419.aspx
Keeping that in mind, these are the components you're going to need to keep in mind for deploying your Edge successfully:
Edge Servers
Reverse proxies
Firewalls
Directors (these are optional, and if they're included, they'll be located on your internal network)
Load Balancers (you can have DNS load balancing or a hardware load balancer (HLB), but for a single Edge Server, this isn't needed)

[rito2k]

I would recommend using Web Application Proxy as Rev. Proxy, since TMG has been discontinued AFAIK. Web Application Proxy is a WS2012 builtin Server Feature. Instructions to deploy can be found here: https://www.microsoft.com/en-us/download/details.aspx?id=44940