Since your new to the greatest automobile ever built, you need to understand this, 1986-1988 Mustangs were produced with a "Speed Density" type of computer, this set-up does not use a MAF, instead it uses other sensors to determine proper Air/Fuel ratio's and such, this is a "set" system.
The 89 and up stangs used the Mass Airflow Set-up, this allows for much better driveability and the ability to compensate for performance items.
For now, remove the "squirel box" or air silencer in the fender and get a nice K&N filter, put it in the fender later, as you need other items as well. hope this helps.
Also, my opinion, and guy's this is my opinion (actually after Rick Anderson told me this) so don't slam me too hard as i alway's do when i say this.
As far as the Cold Air thing is concerened, it has been proven on the dyno that it is the VOLUME of the air that your motor recieves that matters NOT the temperature of it, NOW!, I'm not saying that cold air doesn't matter as it certainly does, colder air is more dense therefore we are able to cram more air into the engine per revolution, once again it proves that MORE air is the key. Ram air set ups only work above around 90mph and they usually are sucking up hot air right off the ground so i don't recommend them until your blown or damn fast.