I have the D70, Ikelite Housing, Same port and strobe set up you listed. I have used the set up during a 10 day Cozumel trip and several local trips here in Minnesota for a total of about 50 dives.
As for your first question - Yes you need the close-up adapter mentioned by B&H. I have the B&W brand and I am happy with its performance. Just remember to put in on before your dive or the system will not work. Not that I have done that (twice).
The EV controller is helpful but you don't have to have it. The DS125 power can be manually set on the strobe. The EV controller just gives you better control by providing more power settings. One thing I liked is that since it mounts close to the camera, you don't have to reach far to the strobe to change power settings.
Also not necessary but nice are longer arms for the strobe. I found that I got better results with the strobe further away. I ended up using 11" Aquatica arms for the DS125 (Available at B&H as: "TLC Arm Section - 11" - Double Ball).
I also use the Aquatica Large Knob Ball-Joint Clamp. I felt that it gave me better control and holding power with the longer arms. It is also eaiser to control when diving with thick gloves.
Good luck with the system. I have been pretty happy with the the results so far.
Chris
D70, Ikelite Housing, DS125