IC2 handles fluid the way Forge has handled it for years, implementing IFluidHandler. As a result of the capability system however, that's gone completely in 1.11 so porting will be fun. In the mean time however, other mods for 1.10 have forgotten this, and act as if it's already gone. IC2 has lots of elaborate code to handle all these situations (as the same happens with inventories, IInventory being forgotten in favour of the item capability), because we're kind like that. I think the only scenario that things don't still work is when other mods look for the fluid capability on IC2 machines, because unlike machines that have inventories, there's no single class all the fluidy machine use. I'll add a good enough work around for it soon, the situation will resolve itself by 1.11+ anyway.
As for power, EU isn't RF, Tesla, Forge Energy or anything of the like. You've always needed other mods to convert to and from it, and things are no different now. The only difference is that the way Tesla and Forge Energy are implemented allow the converting to be a little less intrusive, in terms of needing special blocks or cables at least.