Gst registration

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i want to register under GST as a Caterer ( Catering Service ). 

1] Can i opt for composition scheme . If yes then what will be rate applicable 

2] After selecting composition scheme below its asking for '' Reason to obtain registration'' so here can i accept voluntary because its turnover is below 1.5cr

3] I had a service tax registration from 2010 so in commencement of business which date to be selected 11-Nov-2010 or the date of making registration .