Remote Web Workplace does nothing more than you let you download an RDP file.
The RD Gateway Role is already installed. That's how you remote into all of your computers without having to open ports for all of them. Remote Web Workplace is just an easily accessible portal. If you actually take a look at the RDP files that get loaded, you'll see that is already using RD Gateway. If you check out the settings in the RDP file, you'll see the gateway.
Example:
Your RD Gateway Address is the same as your RWW domain name. remote.domain.com