Look up the posts by Sentrastyle here on the Forums. He has boosted his GA16i, which is TBFI just like the E16i in question. You'll have to most likely use an additional fuel injector, as well as some solenoid system to spray it when under boost. You'll be limited on boost unless you figure out a way to adapt a later model MAF sensor to it.
Here is a link to his posts:
http://www.nissanforums.com/e-ca-ser...i-pistons.html
In regards to the oil issue; use the oil pressure sender on the engine block to feed the turbo, tap the oil pan, and then drain from the turbo downward. Most simple solution; just make sure there are no kinks on the oil drain or you'll crap out your turbo seals and possibly run your engine dry.
If the E-series is anything like the GA-series (which is is
and has a lower compression ratio), you won't need much boost to make the engine come alive. I used a tiny K03 turbo off a Volkswagen 1.8T, and at only 4 lbs of boost, my car booked like nothing else. I would keep boost around 5-7 lbs since the stock MAF sensor can probably only handle that much before crapping out.
What type of fuel management are you going to use? S-AFC 2, Megasquirt, eManage? I don't know if any of these are compatible with the E16i. You might try and get a hold of a complete E15ET intake manifold and ECU. Check EXAclub.com, they have all kinds of goodies for sale. As for a turbo manifold, you could probably chop the factory flange off the stock manifold and weld on the appropriate flange, or make your own; whatever is easier.
Lastly, what turbo do you plan on running? You mentioned CA18DET, which has a T25. That would be a good choice with engine management; otherwise I would chose something like a T2, T20, or smaller. There are some good small turbos out there that require less fuel modifications for good power gains.