Does it have tempering valve for hot water? Does it conform to any standards?

It doesn't have tempering valve for hot water. It conforms to any standards.

Does this have music? And if not… which model has music, changing LED lighting and fits 2 people?

Does this have music? And if not… which model has music, changing LED lighting and fits 2 people?----No, it doesn't have music. You can check with this one that have FM radio & loudspeaker. https://www.homary.com/item/71-acrylic-led-water-massage-bathtub-decoration-transparent-in-white-27174.html

What are the power requirements for this tub

What are the power requirements for this tub---It is US plug and 110V，60HZ.

How tall is this tub and is it easy to get in and out of with bad knees? Love this tub

Q:How tall is this tub and is it easy to get in and out of with bad knees? Love this tub A:The height of this tub is 27.56inches.and it is easy to get in and out.Please don't worry.

How tall is this tub and is it easy to get in and out of with bad knees? Love this tub

Q:How tall is this tub and is it easy to get in and out of with bad knees? Love this tub A:The height of this tub is 27.56inches.and it is easy to get in and out.Please don't worry.