Hello Zeff, I'm sorry I do not know the difference between those motors, but I will try and ask some of my friends from the Phillipines. I would assume there are no differences - but this also depends on what generation of the 16A we're talking about.
If you're not going to use the car for anything more than the occasional flog on the motorway, then I suggest that you just get the OEM clutch for a DC2-R.
For a flywheel, I prefer as light as possible - so anything from Fidanza is good or we can also supply one that is around 8.8lbs or about 4kg. I'm pretty sure your plans won't be much of a surprise if you keep posting visitor messages instead of private messaging me with your queries. Haha.
Thanks for your message and inquiry. In terms of the best final drive, I would advise getting the 4.9 as it offers the most torque multiplication for the rather torque-less B16B. Be sure to clean the factory magnet inside the transmission case and I would also advise that you check the input shaft bearing and the differential/LSD carrier bearings. We also sell the LSD bearings, and a set of our powerful transmission/sump magnet plugs are also a good idea if you don't already have them.
As for who to purchase from, it's entirely up to who you are most comfortable with.