How would you be able to tell if your a good singer?
When you go to a kareeokee bar and people don't throw stuff at you
People don't get a painful look on their face when you sing.
Record yourself and listen. The answer will be obvious. :)
if ppl like ur voice and not complain
Refer my answer for your second question REGARDING DANCE.
If you don't shatter glass when hitting high notes... See link below.. http://youtu.be/VCzWWT59quI