Absolutely no problem changing up the carpet. Things to watch for......make the transition in a doorway, an opening or along a visual break in the rooms (like the corners of the walls). I would stay in the same colour range, but just go to the other end of the spectrum rather than change the colour completely.....like light grey going to dark grey, not light grey going to navy blue. You want the separation but an easy transition on the eyes.

What is the rest of the house like? Would you like overflow sleeping areas or more storage? If you can't raise the floor (and the ceiling?) you might consider building in some comfortable seating/storage areas that use pillows/cushions and play up the multi-level idea and make it look intentional. Similar in concept to the stepped couch.

Your lounge looks like it receives a lot of sun so you might like navy, turquoise, or emerald green for the room. Whatever color you pick, leave the valances (?) above the windows close to the color of your air conditioner, so it won't be too obvious. Use lamps and update the ceiling fixtures. Bamboo blinds might look fun on the windows. Look to the kitchen floor for paint colors in there. It appears the range hood is way too high to be effective. Is that just the perspective?

Hi there. If the tile you have has character, you could pull a colour from some of that character, for example if the tile had a beige fleck through out you could use a similar beige tile in the bedroom, otherwise just choose something that compliments the tile well to create a soft transition. Then use the colour of the existing tile in the room somewhere, with your bed linen for example or bedside lamp. Feel free to share an image of the existing tile.