Spike,
EK pay for three kids education at any time. So when the older kids turn 19, or no longer need to be paid for, the younger ones can join the system. This can help if the ages are spread, not much help if all close together I guess.
The medical insurance is a set premium for a family of Mum, Dad and three kids. To add extra kids to this (and its compulsary even if you have another health fund up and running), you pay extra per extra child. The extra amount per extra child, is about 3/4 of the family rate, and the amount of benefit for the extra children is also reduced. By this I mean the amount they will pay per year for dental, number of nights hospital cover they will pay etc etc. Best you ask when interviewed about this, as they will give you all the details you need. Once again as the older kids no longer need this the younger ones take their place in the scheme.
You also get a free ticket home once a year for a family. Once again this is for Mum, Dad and three kids. As you have more than three kids you will be able to buy an ID50 ticket (firm ticket, discounted 50% from the full price fare) for the remaining 2 kids to ensure everyone can travel together. You will find out that flights over here are always full, and the chance of getting on with an ID90 in economy class, during holiday time is zero. They normally do not offer ID 50 tickets on a lot of flights, but make an exception when its for extra kids etc. It takes a few phone calls, emails etc to organise, but not too hard to do. Also, remember that when joining you will have to buy the 2 ID 50 tickets as well, as the rules are the same as above. And again once the older kids fall out the top of this scheme, the younger ones are then covered. Might be an idea to ask someone you know over here to let you know how much one of these ID50s is going to cost.
As stated above, it is hard to get by with a bunch of kids over here on an FOs salary. I wold probably ask how many FOs are already in the company, and how many more aircraft are expected at the interview as well, to get some guess at how long the seat change will take.
Also if you know any of the new joined DECs over here, ask them how they all got summer leave this year. Might be a good thing to add to the contract as well. I know quite a few 777 crews that were here already that missed out on any of their leave bids are also interested.
Don