This may help
http://www.hia.ie/ci/health-insurance-comparison
re your questions.
Its a nightmare area
I think the cost of this may frighten you so have a browse of the different products first. My neighbour pays 8,000 per annum for two adults.
There will be a waiting period for both general medical state and especially any pre-existing.
Dental is available as a bolt on but its more big dollars
The essence of health insurance is that it allows you skip the queue for most elective stuff.
To illustrate I was last Friday with my 87 year old father in law to see a consultant who was paid cash to see, ie no health insurance.
A procedure was suggested and he told us go book in with the secretary.
She asked: private or public: we said public: she said 18 month to 2 years.
I said private: she said Tuesday at 10.
Then there are some policies which have more of an inpatient focus, so maybe you get a better room etc etc.
Other policies have more of an out patient focus.
Then some policies cover all hospitals for everything, others cover only some procedures on some hospitals.
Finally the policy terms change very month so quotes are only valid for till the end of the month the quote is issued.
Hope this helps