1]. You will be required to apply for the Permanent Account Number for the purpose of your Income-Tax matters. Also you need to apply for obtaining your profession tax number for paying PT. if you carrying on your profession from an rented premises then you will be required to take an No Objection Certificate from your Landlord to carry on the consulting business.
2].Yes you can put any name to your firm which you like, there’s no restriction. For Sole proprietary concerns no registration is required to be made anywhere. However you can apply for the Shop Act Licensee under your respective state law.
3]. You need not pay Service Tax until your Gross Receipts exceeds Rs.10lacs in the previous year. After it crosses the threshold you will be required to obtain the Service Tax Registration no & collect & start paying service tax.
4]. If your gross receipts cross the threshold of Rs. 15lacs in the previous year, then from the subsequent year you will be required to apply for Tax Deduction Account number & will be required to deduct TDS on any payments made as mentioned below. You will also be subjected to Tax Audit u/s 44AB of the I-T act & will be required to get your books of accounts audited from a practising CA
Professional fees, Rent, Commission paid, contractor payment etc…