Upgrading Nokia Lumia 1020 to Windows 10 & Project Astoria questions

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Thank you guys for all of your nice messages :-)
Btw, I also conveyed your greetings to my dad today evening, he is very happy with his phone now :-)))

And believe it or not, I got myself another Lumia 1020 today evening hahaha (I simply had to buy one for myself, it's really an awesome phone :-)).

I have just upgraded this new Lumia to WP10 build 10586.107 (before doing so I unlocked bootloader with WPinternals and created a backup, learned from experience :-))
But I cannot get Lumia Camera app on this build for some reason (it wasn't even present on WP8.1, perhaps the owner had never installed it).

Now, the question for you experts:

1. Would it be possible that I flash this new Lumia 1020 with the firmware from my fathers Lumia? Would that approach work? And then simply restore the backup on my Lumia that I created for his phone? Would that be possible?
2. Or try to rollback using WDRT to WP8.1 to see if I'll get Lumia Camera (Nokia Camera app) there? And from there upgrade again to WP10 to keep Lumia Camera and then prevent Store to download the update for it.

Please suggest what would the the best working approach in your opinion.

Thank you guys again!!!