Opt form Composition to Regular under GST

My Client is registered under GST Composition scheme for his Business activity -- Sweets Shop and paying GST under Composition. 

Now, he want to pay the GST under Regular Scheme by availing GST Credit on Purchase and to Pay GST on Balance payable amount. Also, He is in process to Add one more business activity of Fast Food Separate branch under existing GST Number.

My queries :-

1.  Can he opt for regular Scheme again from Composition Scheme?

2. Can he add one more business activity of Restaurant/ Food Outlet under existing GST Number/ Business.

Please suggest.