I am planning a road trip though Europe this summer. The car is registered in Ireland. Is there any documents I need to drive in the countries listed above. I am aware I need a sticker for the Motorways in Austria and Switzerland.
There are a couple of things you should do.
An International driving licensed is not required, when your driving license is in a language that the police can read. They have to verify that you license is up to date an valid. So, when your driving license is in German, French, Italian, or English, you should be fine, and probably there are even more languages acceptable, but if your driving license is in an obscure language, I would bring an International driving license.
Furthermore, you should make sure that your car insurance covers all the country you want to travel through. It is not required, but it makes your life easier when you bring your green insurance card with you. Other than that, you should also the car registration document (Fahrzeugbrief) and your passport / identity card.
As you already mentioned, you need a sticker for the highways. In Switzerland, there is only one option. You have to buy a sticker that is valid for a calendar year and costs 40 Swiss francs. In Austria, you can choose between 10 days, 2 months and 1 year.
Other items to carry
In Switzerland and Liechtenstein you need a warning triangle. If your car requires to have a fire extinguisher in your home country, it is also required in Switzerland.
A very good resource for all these things in Switzerland is available online.