Does the light will keep on? or will it go off. I need it dark in my room when I go to sleep.

no, it will be off after seconds.

Can I change a longer charging cord?

yes, of course.

Does it require a fast charger adapter for fast charging?

as they described, a 9V 1.67A adapter required.

My wireless charger has stopped working. How do I use the warranty?

contact customer support

the plug port has become loose how can I fix this ??

check the warranty and contact the customer support

Will it work with Lg V20 ?

yes, mine works perfectly.

Does it support 7.5W charging on iPhone 8/X?

Yes, 7.5w for iPhone X, 8 and 8 plus.

Does it have to be perfectly aligned in the center for fastest charge?

No, you can charge your phone at any direction.

I use a wallet case on my iPhone 8 Plus, will this charger damage the credit cards?

you'd better not.

can i charge my phone overnight?

I do this almost every day.