No it won't hook right up. The ignition is different as it has a seperate ignition coil. Also, depending on which 5efhe you get, you will have the ACIS system that you may want to make active and to do so will either require the 5efhe ECU or a RPM switch. But you can just leave the extra intake runners on the ACIS open all the time, but gas mileage will suffer. There are a few companies with 5efhe's in stock here in the US, but most will have to import them. Just be preparred, as this engine is getting hard to find and thus expensive.
Difficulty is relative. But in either case, you are switching to an external coil. Just one you use Toyota parts and the other you use aftermarket. It is more a matter of cost and availability. If I had to say, I would say modifing the Toyota one is easier, but more costly.