Maybe the kitchen is further away and on smaller pipe.
The volume of water that comes out of the tub faucet is much greater than the volume of water that comes out of the kitchen faucet. Let's say that the bathroom is twice as far from the water heater than the kitchen, so twice as much water has to be run to get the hot water. If the tub faucet allows more than twice as much water to pass through, then it will get there faster.
No! The Hottest Water On Earth is 407 celsius and Venus Is Hotter Than That! You Can't Get Water Hotter Than Venus!
No, you will have different temperatures of water inside the water heater, which will make it difficult to get a consistent temperature out of a shower valve or faucet. The heater will also not work correctly or efficiently.
hotter than cold water
Yes, but not at atmospheric pressure (which is the pressure of your kitchen). Steam can be hotter than 100 degrees celsius under pressures higher than this.
Burn your tongue and throat is about the only issue. Hot faucet water is no different than cold water you heat on the stove or drink in your coffee.
You cannot do this without a way of stopping the water. The sink sprayer is hooked up through your kitchen faucet for a reason. When the faucet is shut off, no water can come through the sprayer. If you hook up the sprayer to a water filter, the handle on the sprayer cannot handle the pressure of the water system and will continually run when the handle packs it in, more than likely when you are not home!
It depends on where you are. If your water comes from aquifers that are in limestone rock and you are near an industrial are it is likely the faucet water will be slightly higher pH than the rain water.
No. It takes much more than water pressure to turn on the water faucet. At most, there is a leak if anything at all.
Shutting off the valve doesn't drain anything. You need to open something lower than the faucet and open that faucet to let air take the place of the water.
A lifetime warranty only lasts for the life of the company that sold you the faucet and may not cover every component of the faucet. In general, if you have the warranty you can send the faucet back and they will send you a new one provided that the defect is covered. (Some leaks, however, may be caused by things other than the faucet itself.)
Very simple. Run each faucet until there is no more air. This usually only takes a minute or two per faucet. Remember air is lighter than water and will quickly rise, thus exiting the faucet additionally the strong flow of water out of the faucet is a huge plus.