I second patricia, make it all the same flooring. I did the 'wood floor in the walk in closet' while the rest was tile, ended up taking it out and just tiling everything, the threshold was collecting dust and grime and annoying for my laundry cart.

LED - I don't know that you'd need the dimmer kind / but this happens to be. You'd need a wall switch that's right for it.

There are lots of possibilities! You could try a chandelier, for example, if you want a very glamorous look. If you don't really have room for a chandelier, try a ceiling flush or semi-flush mount. Wall sconces can add another pop of light. LED tape light could be great if you have, say, rows of shoes in a display and want to illuminate them like you might see in a store. You have some great options here. Let me know if you have any questions.

And you can have different designs in different rooms but there should ideally be some elements which should be the same throughout. For instance, I like to use the same wood veneer finish throughout, but the designs could be different in each room. Or like Cornerstone Design says, the children's room alone can be different. I prefer not to make the children's room something that is too 'kiddie', so I opt for a more classic design for the Master bedroom, but keep it simpler and similar for the others, with some small differences. Sometimes clients feel cheated if they don't get something different for each room, so it is the job of the designer to convince them