I am not familiar with this airline, but the link you provided reads:
Is an infant entitled to any baggage allowance?
Infants are not entitled to any baggage allowance with the exception of a pushchair / foldable baby carriage / infant car seat per infant (carried free of charge).
Ok, infants can bring a stroller and/or carseat for free. I see this sentence as a little ambiguous as to whether you can have both or just one free of charge.
One of these items will also be carried free of charge for children (between the age of 2 years and 14 years old).
This sounds like for 2-14 year olds, you can have EITHER a stroller or a carseat. This would lead me to believe you can have both for a baby.
Please note that prams and pushchairs shall be checked in with other baggage and will be carried free of charge only if the user of the equipment is travelling. However if no infant or child is involved, these items will be carried as checked-in baggage for an additional fee.
This looks like the stroller at least would need to be checked in regularly, and not gate-checked (though this might depend on the airport too). The kid needs to be travelling with you for the items to be free.
It looks like that IF you have a seat for the infant, you can use the (air plane approved) car seat in the seat. I would expect it to go in the cargo hold otherwise.
In my experience with other airlines (Delta, Lufthansa, Virgin America, United, KLM, Alaskan) I have never had to pay for a stroller or car seat. We usually check the car seat(s) in the luggage, and gate check the stroller. Next long flight coming up we will use the car seat on the plane, since we got a ticket for our youngest too.