Part 4:

the temperature of the griddle.

I would STRONGLY advise that you just abandon the griddle if you have the funds to purchase a proper lower heater (the T8280 is not a premium device, but at 1600 watts, it is much better than the griddle, especially if you can pick one up for $100).

Even with a holding device, you need to have a proper nozzle to match the size of the chip that your are heating as well. The nozzle needs to be placed fairly close to the chip so the hot air completely saturates the chip (you will have to find a sweet-spot for your air flow so that you don't blow components off the top of the GPU/CPU/Chip you are heating.

As you are learning, I would also recommend the fine wire OMEGA thermocouples placed UNDER the chip so you can get a better ideal of the actual chip temp you are reaching, instead of the airflow above it.