Will it charge with a battery case on the phone?

I don't think it will

Is the adapter that comes with the Galaxy S9+ at purchase suitable/good with this product?

of course, my s8 can work no problem.

So I've had this about 4 months now and all of a sudden it no longer charges my iphone. What is the issue?

Try turning your phone off and restarting it. It worked again after a restart for me.

Mine broke in less than two weeks, is that normal for this product?

No. I haven't had any troubles with mine since I bought it.

how long is the cable? I would like to know how long, so I can order a longer one if needed.

about 3ft

Will this overcharge s9 plus phone. and can u talk on phone while charging ..

yes, with an iPhone 8 Plus, I can send message and make a call and it will continue to charge.

I have an s9 can it be face down while charging?

It doesn't allow for face down charging.

does the adapter need to be plug in when you are charging?

yes, it’s how it gets electricity to be transferred to your device’s battery. the charger itself doesn’t keep energy inside like a battery, so it has to be plugged in the whole time you’re charging.

Will it work with a popsocket?

It will not. Will work with most cases but a magnet or popsocket in the way will not work

should I remove the phone case when charging?

It definitely does in a plastic case. I read that metal cases could be a problem, heat and maybe connection.