That sucks, man. I think relatives are the last to go to for recommendation, for some reason always turns out terrible. Then you can't scold too much too because have to take into consideration your relatives.

Can't tell you the exact price, but usually contractors charge per square feet. This includes labor and materials except tiles. For Kuching, last I heard ranges from 4.50-6.50 psf.

Depends on what sort of tiles, but why would you want to do it anyway? Tiles, especially in high traffic areas are meant to be resistant to wear and tear. No paint can even come close to it. Unless there's some sort of new technology etc. in paints, haven't heard of it.