Configuring Edge Transport Server Cloned Configuration

Hey All,

Hope my Question find you well. I am currently preparing to deploy Exchange 2010 Edge Transport Server Cloned Configuration in a company's DMZ. Currently they are using some other appliance in the DMZ whichis responsible for real time sender IP reputation checking,  Spam rating, AntiVirus &  anti-malware databases real time  updates, Heuristic rules updates. For some reason we need to change this appliance.

Here is the company's current Exchange Organization Looks Like:

• Two Exchange 2010 Servers with Hub Transport and Client Access roles.
• Two Exchange 2010 Servers with Mailbox role.
• The Exchange Organization operates in the same AD site.

I have checked on best of MS Teachnet Library documents and, i am able to get good understanding about Edge Transport Server Cloned Configuration.

Here are the things which i need professional explanation on:

1. How the Hub Transport Servers load-balance Outbound mail traffic across multiple ET servers.
2. How the Edge Transport Servers load-balance Incoming mail traffic across multiple HT servers.
3. It is a best practice to deploy the edge subscription file from one ET server to one  HT server. Each HT server will send/revive from one of the ET server.
4. Can i use the HT servers NLB IP on the ET servers to send incoming mails to HT servers.

Please explain this points for me to fill on the gap i have in mind. I appreciate if clarify the points in the forum than sending me the Web-links.

Thanks & Cheers!