Hydrogen water is generally recognized as safe (GRAS) by the FDA, meaning that it’s approved for human consumption and not known to cause harm. There’s currently no industry-wide standard on the amount of hydrogen that can be added to water. However studies show that even at very high concentrations there is no evidence of any side effects. Here is one official study:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7102907/

It is known that hydrogen-rich water reduces oxidative stress and has a good effect on the kidneys and bladder.
Effects of hydrogen-rich water in a rat model of polycystic kidney disease

Hydrogen Water and Alkaline Water are not related. Alkaline Water has dissolved minerals while hydrogen water has dissolved hydrogen gas. This means that if you want to drink hydrogenated alkaline water you can just use alkaline water with your compatible generator.

The recommended daily water intake is between one and three litres. We recommend that you drink only hydrogen water, although anything more than one glass a day will be highly beneficial for regulating your oxidation level.
In thisvideo Dr. Shigeo Ohtamentioned that one glass of water a day is sufficient

By mass, about 96 percent of our bodies are made of four key elements: oxygen (65 percent), carbon (18.5 percent), hydrogen (9.5 percent) and nitrogen (3.3 percent).
Source

Yes. The only effect of hydrogen-rich water is to help to maintain a suitable oxidation level for good health. It has no contraindications.

Yes. It’s safe to give it to any kind of pets.

No, because the hydrogen will be released while water is boiling

Yes, If you heat the water without boiling it, it will keep its hydrogen and electric charge.

Yes. It eliminates free radicals from the skin. Hydrogen water can be applied with a cotton pad and silk sheet or directly to the skin and it penetrates within a few minutes

When our level of oxidation is high, the body refuses to convert food into energy, because this further increases the oxidation. The antioxidant charge of hydrogen water helps to adjust the level of oxidation in the body, which enables food to be converted into energy, instead of being stored as fat.

The body refuses to convert energy into food when our oxidation level is high, because burning fat causes even more oxidation. The antioxidant charge of hydrogen water helps us to lower the level of oxidation, enabling the metabolism to transform fat into energy. However, the body never loses fat deposits unless we burn more calories than we consume.

Zero, zilch, zip, nada

Everyone is different. Some people feel more energy and better hydration instantly, while others do not notice any change at all even after week of drinking it. The same can happen with taking any antioxidant but this doesn’t mean it’s not working in the background.

Yes. Any water can be enriched with hydrogen.

Yes if the container is glass and hermetically sealed.

Platinum plated titanium.

No. There are vitamins, minerals and phytochemicals in plants which play an important role in oxidative stress prevention.