Why is it easier for you to use the incorrect voltage?
Did you overlook this line from the tutorial you linked to: VCC which is the positive and needs 3.3V
When the tutorial says use 3.3 volts supply, why do you ask "how do I make it work at 5 volts" ?
Some of these displays do need a bypass capacitor on the VCC to GND terminals to avoid distorted output. But, do not assume this will resolve your use of the display at 5 volts. It is a 3.3 volt device. Using it at 5 volts will most likely result in an early death.
Oh, yes, your last question. No, PWM pins are only PWM when you write to them with an analogWrite() function call. Otherwise, it's just an ordinary digital output.