Confused with X90J Features, need some clearification (Dolby and Display)

Hi Guys.

So last week I received the X90J 65 and I started playing with the settings.

I know the TV supports Dolby and 120hz but I am confused for some features.

1. Does it refresh at 120hz rate when no external HDMI is used (like builtin netflix, youtube apps, or external ssd) ?
2. Do I still get 4K If I enable 120hz from Hdmi Input settings?

Regarding the Sound, it says it supports Dialog, Sport, Dolby etc ...

1. Are these settings available without any additional device such as soundbar or it is a must to have one in order to apply one of the above sound modes.
2. Some audio modes from the Settings app, do show the INPUT HDMI 3 in the header, does it mean those are applied only on eARC HDMI 3 ?

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Thanks for your time :D