3) Someone can discover your WPA key quite easily. You can try it yourself with reaver. I've tried it, It works on the DIR-615. Problem is that there are some routers where the WPS service remains active even after you've disabled it from the web config. Not sure about the DIR-615.
4) TR-069 is for TM to remotely configure/manage your device from their ACS (Auto Config Servers). I know they use it to change settings on the BTU but haven't seen it in action on the router. Not a really a biggie, if you ask me. e.g.: if you forgot your password of your router, they can use TR-069 to change it for you instead of having to walk you through resetting the router over the phone.

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Added on February 12, 2012, 3:37 pm
No problem. Come see me at HQ and I'll set you up. The rest of you guys will have to wait till your contract is over. New prospective customers keep checking the website. Any questions, please email mok@tm.net.my with subject line "Just like Thailand"