Long flight time quad/hexacopter build questions

I would like to build a hexacopter that has
1) Flight time minimum 30 minutes.
2) It will carry Gimbal and GoPro Camera.

Questions
1) Should I build hexacopter or quadcopter?
2) Which frame will be a good?
3) What motor and prop combos will be good?

If u have a good berget . Build a octocopter in a  quad frame    .... U'll have to design your own frame . Or u can buy a tarot frame and swap the motor mounts . Or make a 3d printed ones ..... Btw which camera I'll be  fixing to the rig

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