Hey! let me take a shot at helping out:
- I recommend looking at the content examples level streaming map, it’s very helpful on how level streaming works. as for lighting, you could use static lighting everywhere, if you don’t care about shadows.
- you have options here. you could open a new map, which would be the indoor map, or just literally teleport the player somewhere out of sight, like below the land, and stream the indoors scene in. both of these are done with blueprint nodes.
- you can make and sculpt landscape in unreal engine itself. it works pretty well for most things. you would want to import rocks and caves to place from 3ds max though.