Doubt on Registration

Dear Professionals,

One of my client is Vegitable Seller. He has a shop & sells fresh vegetables to consumers and some hotels.

Since he is supplying to hotels his monthly turnover come up to 4 lakhs.

Queries:
1) Whether GST registration is required for his business since yearly TO exceeds limit?
2) If I file his ITR by using ITR 4, (without GST Registration) showing TO as Rs 48 lakhs, whether GST Dept will ask for any details if they reconcile the sales with the ITR.

Please clarify.