Summary: in this tutorial, you will learn about C variables that allow you to manipulate data in your program. A variable is a meaningful name of data storage location in computer memory. When using a variable, you refer to a memory address of computer.
Overheating of the CPU caused by a temperature problem is definitely a bad sign as it can destroy the processor and can cause instabilities in the hardware of the system. This can lead to it rebooting as well.
Load is a term for how hard the device has to work to power whatever is attached to it. High load means the output power is high, low load means the output power is low. You can increase the load by, say, connecting a second device to the output of the generator. Assuming the voltage is constant, the current will be higher (since there are now two deices powered by the generator). That means that the equivalent resistance of both deices in parallel will be lower than that of a single device. So, increasing the load means decreasing the resistance of the load. This may be counter intuitive, but usually devices are not rated in resistance-they are rated in input current or power, so the load follows that.