What comes in the box besides the charger?

a USB cable

Will it damagebattery if the phone be left on it when fully charged ?

I leave my phone on it overnight and hadn't find any visible damage.

Does this product have a safety rating? ul, ce, csa, etc.

Sorry, I don't know if it has any safety ratings but it does work very well

Can I use it with iphone with Qi receiver?

My iPhone 8 can't work with it, no idea about other phone models.

Is it normal for the charger and phone to stay hot the whole time the phone is on it even despite the fact the phone is fully charged?

No that is not normal. you can contact the seller.

I'd like to know what the input and output voltages

it depends on your phone model.

Ive purchased this item several days ago and notice it makes a loud clicking sound when charging. Is this normal?

I haven't noticed any noises from it.

Will this charge an iPhone 8 if it is placed horizontally?

yes, it can charge your phone both vertically and horizontally.

I am gonna travel abroad, can this only be used in USA (110v)?

I use it in Ecuador, it works fine!

Is it normal that the charger suddenly shuts off on its own? I then have to unplug it, wait for a while, replug it and then it works again...

I am not aware of this difficulty.