What is the scenario where you don't have the ironclads after one turn, I tried with the July 61 setup, and they are added.
About your test, were you simply reverting to a backup or were you recreating a new game? It is normal to have the same outcome, if you reprocess the exact same turn, this is how I can fix bugs
Only the evasion value is used, with some adjustements if the stack is small (4 or less unit) or in bad weather, nothing more.
1. engineers are not combat engineers. They can speed up earthworks too. Naval engineers speed up ship building.
2. they have nothing special, except to serve as light escort to transports, or block riverine supply, they can't even bombard efficiently, use them as the patrolers they are (you can also use them as spotter)... there is a problem for now, we have to make some room for them as the buying interface have only one slot left, but you will be able to buy more
in the next update.
3. We plan to add some 'chrome' scenarios with merchandises and cottons, or even contrabands (slaves) units in the future.