Will I have a nice body even if I have bad scoliosis?

Varies. In general, curvatures over 45-50 degrees do tend to steadily progress and can potentially cause cardiac and pulmonary problems and also an enlarging "rib hump" where curves less than 45 degrees are much less likely to progress or cause problems. Don't hesitate to see a specialist to discuss the specifics of your case.
Diamonds have facets. Everyone wants to be attractive, but this can mean different things to different people. Some are attracted to facial features others to legs. So yes you can still be attractive even with bad scoliosis, but remember, true beauty comes from the inside!
This depends on . The symmetry of your body and balance which is related to the size, type and location of your curve. The more symmetric or balanced, the better you appear.