I will try and answer your questions accurately, but it is quite late here in Dubai and I am just off to bed, but here goes...
The meal allowance is only just enough to satisfy your requirements whilst away, that is what it has been designed to do. It will not supplement your income in any way at all. The average daily allowance is between US$70 and US$100, that is for a 24 hour period. It is not enough.
Education support is provided. As I understand it, you are given Dhs10,000 and then 90% of the school fees above this. I have two kids in school, the fees are around Dhs8000 each per term. So my total schooling bill is Dhs48,000 (US$13,000) of which the company give me Dhs45,200 (US$12,300) so I am Dhs2600 (US$700) out of pocket each year. But that does not include any extras that you have to pay for, from uniforms and sports kits, to after school activities and trips. But that is me and the school that my kids go to is not the most expensive by a long way. Nursery / Kindergarten charges are your own responsibility as the allowance only applies from 5 years old.
To summarise, the trip alllowances are appalling and I am often digging into my pocket (credit card) to pay for things whilst away and the education allowance is ok for me, but others do suffer quite high costs above the allowance.