Coil: Try subaru, pretty much ideal for a beetle running wasted spark.

Re IAT, there is theory, and then practice. In theory yes, you want MAT + MAP to control things. In practice MAT is an utter lie due to sensor soak and airflow and radiated heat etc. In practice you want ambient air temp or similar. My idea to use the fan to keep the sensor close to air temp was based on this. Feel free to run a MAT and IAT and Ambient and post IC/pre TB etc. The more temp figures to correlate and model from, the better. But one well chosen place will work OK.