You can find the following key information for business:

Starting a Business in Ireland

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

http://www.pointofsinglecontact.ie/registering-a-business/registering-a-business.html

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

Taxation and Social Security

http://www.pointofsinglecontact.ie/tax/ 

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

Establishing a Place of Business

http://www.pointofsinglecontact.ie/establishing-a-place-of-business/establishing-a-place-of-business.html 

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

Health and Safety

http://www.pointofsinglecontact.ie/health-and-safety/

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

Employment Rights

http://www.pointofsinglecontact.ie/employment-rights/employment-rights.html

Work Place Relations, Employment law.

Funding / Support

http://www.pointofsinglecontact.ie/online-services-for-business/online-services-for-business.html 

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

Licences 

http://www.pointofsinglecontact.ie/starting-a-business-in-ireland/table-of-licence-and-permits/licences-and-online-services.html

Provides Table of licences information.

Closing your Business

http://www.pointofsinglecontact.ie/Irish/D%C3%BAnadh%20Gn%C3%B3/

Administrative procedures involved when closing a business in Ireland.