Irish Citizen Living in the UK ~ Non-EU Parents

I'm an Irish citizen; my (non-EU) parents are getting old, I would like to bring them to the UK to live with myself and my wife; I can financially support my parents while/if they live with us.

I suspect my case falls under the 'EEA Family Permit' / dependent parents; however, I appreciate any guidance and instructions as to what I need to do to get my parents here permanently.

Facts about my case:

1- I am a Republic of Ireland citizen (naturalised). I live and work permanently in the UK; I have been living here for 4.5 years. I am married with no children. My wife is a non-EU citizen.

2- My non-EU parents, whom both are retired (65+ years old) live in their country of birth (outside the EEA); they do not have any other citizenship except the country in which they live.

3- My only sibling is a sister who lives permanently in Canada. She hasn't visited my parents in the past 3 years - they have not visited her either.

4- My mother has had open-heart surgery many years ago, but still suffers from various cardiovascular conditions. She was also involved in a car accident 12 years ago, resulting in multiple injuries which have cause her permanent difficulty in walking (hip-replaced and a few metallic pins replaced in the bones). My father is in good health.

5- My parents visited the UK only once and stayed with us for the duration of their visit (2 months). Their visit visa was valid for two years until mid 2013; however, due to the high cost of traveling, they could not afford visiting us again. I have visited them three times since.

6- Their total combined monthly net income, which only comes from their pensions, is around GBP 600. I have always assisted them financially. However, the only properly documented and visible portion of my financial assistance, are the series of monthly payments which I have been sending in the past 8 months from my bank account. The total sum of GBP 2,500 over an 8-month period - the last transaction was GBP 400.

Concerns and questions:

In order to apply for a visiting visa in 2011, my parents had to demonstrate that they had sufficient financial resources to visit us. They had provided the officially translated version of their monthly payslips and annual income as part of the application pack's supporting documents.

Now in 2015, if I take the 'EEA Family Permit' route, in order to prove that they are dependent on me, their application would potentially contain statements and facts which are to the contrary of their 2011 application.

I understand if their applications under the EEA Family Permit are refused, the chances of getting any future visit visas will be severely reduced.

What are the chances of a successful application?
Is the EEA Family Permit route a viable option here?
Where should I start?
How should I present my/their case?
What else do I need to get in place before I start the application process?

Many thanks in advance for your assistance.

HP