Water heaters should never be set above 120-125 deg. F to prevent scalding and keep operating costs down.
A normal household temperature for water heaters is around 132 degrees. They can all be adjusted from about 120 to 150.
Yes, the tankless water heaters do cost more than the normal water heaters because tankless water heaters are designed to supply hot water only when needed unlike normal ones.
All water heaters should have a pressure relief valve, otherwise they could burst.
I do believe that Maytag does not make water heaters. You should buy from somewhere else. Maybe you should look into buying from Sears or just going there to ask them some questions about water heaters.
American Water Heaters.
To determine the best water heaters, you should know the size you need and the model. You can read more at http://www.waterheaterrescue.com/pages/WHRpages/English/Longevity/the-right-hot-water-heater.html
American Water Heaters
Electric water heaters have not carbon monoxide.
You can buy water heaters from any home hardware store.
GE hot water heaters are made by Rheem.
Rheem provide a series of high efficiency gas water heaters. Several different companies also provide tank-less water heaters, which are very efficient, as well as solar water heaters.
Some of the water heaters uses magnets. Magnets softens the water.