Coming from Unity - Two Questions

Hello Unreal Community, I’ve come from Unity due to consistent large issues with the engine and I’ve been learning more and more about how UE4 functions in comparison so I can begin porting my Android game over but I have a few questions I hope the community can answer.

1) The game I’ve been making is what you could define as a GUI game where you don’t really have any active 2D or 3D game play, just menu based so in Unity I would load a scene on top of a scene such as my inventory then the player could interact with the inventory then finally close the scene down so the focus is back onto the main menu.

How do you perform this in UE4? Is it level streaming? Any particulars I need to be aware of in this situation.

2) The second question is something I never managed to conclude on Unity and for me it’s like a ghost topic where I can never find the resources to learn how to do it, caching resources.

Now my game is art is heavy with the possibility of a combination of over 1GB worth of art work and in Unity to avoid out of memory editors when compiled and ran on Android I simply put in a on demand loading code which works but is incredibly slow.

I’m aware of caching so you can store data in the ram ready for quick access meaning if a device can only handle 50mb at a time I can still make it run but the problem I find is how is this performed in UE4?

Thank you very much for your time

Not sure about second question, i never tried to put as much data into poor android device.

But about first:
you should do it in UMG, it is quite powerful but messed up at few places (like touch interface, better do it yourself on top of UMG that only displays data).
On second thought (but it all depends on your game) you could use 2d engine to display all those things, this will be more coding but probably easier to stream in your huge art. In umg you may be forced to code your own streaming.
Really hard to give you good answer here without seeing your game.

Could you at least tell the genre of your game?