Hi all!
In summary,
1] Go with DNS name - Got it. <<< Need to find out right approach
2] "Request Extension" for Trial - 30 days is generally sufficient, but sometimes you may require additional 5-10 days for completion of Trial. Last time we requested Trial extension, but did not get any response. So, Not sure about right approach. It will be good if Case is generated with a proper response.
3] Support (during & after trial) - Need more formal approach as many times you do not have a site ID.
4] Thanks for the documentation link.
Appreciate your responses.