Well I can't off the top of my head answer any questions for you... I do however own 2 - 95 318ti's and would be willing to help you with parts in any event you need them.
If you replace the air box for a cone filter style, you will need to buy the adapter for the Mass Airflow Sensor.
It bolts to the MAF and has a 2 or 2.5" inlet pipe for clamping on a K&N. Pictured below. That should get you in the right direction anyways! I'd sell you mine, just not sure of it's condition at this point. Not to mention it's so cheap already to get new.
Good Luck, and I hope you love the car!