You can find the following key information for business on the Irish Point of Single Contact website http://www.pointofsinglecontact.ie/ 

Starting a Business in Ireland

Tax, Registering a business, Employment Rights, Health and Safety, Establishing a place of business, Closing a Business.

Registering a Business

Companies Registration Office, Procedures for registering your business in Ireland.

Taxation and Social Security

How to register for tax, Revenue online services, Motor Vehicle Registration, Vehicle Registration Tax.

Establishing a Place of Business

Competent Authority, Documentation to be submitted when establishing a place of business

Health and Safety

Competent authority, Managing health and safety, Safety statement and risk assessment, Health and Safety Authority.

Employment Rights

Work Place Relations, Employment law.

Funding / Support

Local Enterprise Office, SME online guide to funding supports, Enterprise Ireland, Business Organisations

Licences 

Provides Table of licences information.

Closing your Business

Administrative procedures involved when closing a business in Ireland.