Don't count on the wifi. They've been having serious problems with it causing problems in the flight equipment. Because of this it has been switched off and pushed back dates several times for when it would be "fleetwide" workable. If it works, great but wouldn't count on it given the troubles they've been having and how serious to obviously take such a problem.
EI? Can only speak about business class, but EI stands out. In a good way. I've flown to the States with multiple airlines in business but EI stands out. Much better service, hardware, unbeatable prices etc. Entertainment? Simply surf to their website and you can check it out per cabin type.
Just get yourself familiar with their price structures. "Sales" for instance for business class? Grin. They've been pretty much running the same "sale" for about 3 or 4 years now for my AMS-DUB-MCO route. Prices obviously fluctuate a bit depending on demand and supply, but no need to jump on a great sales price in fear of missing out something great.
One very different thing to be aware off; EI business can and does sell out a lot sooner than one is used to with business class on other airlines. The great price/quality ratio does result in higher demand and with a small cabin it fills up faster (are in the process of adding more seats).
Preclearing in DUB is great, but some have been surprised by what that practically entails. Don't preclear until you are done with things like shopping etc. After having precleared no such thing as shops etc. Nothing more but waiting/sitting areas, a vending machine now and again, bathrooms etc. Get your shopping done before preclearing!
Bonus; no need to lug your luggage through CPB when preclearing, all will be automated and just identify your stuff on computer screen. If aditional check is needed (for instance because of having certain items in luggage), they will get pulled up automatically and "magically" appear. No need for you to even touch a bag, let alone lug or cart it around. The whole process will be a lot quicker, much more friendly and with a lot less physical labour than those who've until now cleared on US airports will have become used to.
