17"
You can change any regular toilet for a handicapped, or ADA toilet. I have done it many times in houses and in Mobile Homes. The basic difference is the ADA approved ones are 2" higher. - Every major toilet manufacturer makes such a toilet. You can also buy raised seats by many manufacturers. -Look on sites like e-Bay for examples. These lock onto the toilet and some even have handles.
ASSE /ASTM /ADA
Crane, American Standard are decent brands
Any plumbing supply that sells fixtures
18 inches to center
from 17" to 19" high AFF
below the grab bar
Assuming you have a standard toilet now, it will bolt on the same way in the same position. ADA are just taller floor to seat. Most toilets are 12 inches from the back wall to the center of the drain. Older ones, before 1940 or so were 14 inches and I have come across a few odd ones that are 9 inches.
Yes they do.
Not usually. Check local plumbing codes, they may differ.
ADA (Americans with Disabilities Act) is a set of standards to make things safe and accessible for disabled persons. ADA toilets are constructed in such a way that a person in a wheelchair can easily access and use the toilet without risk of injury. See: http://www.access-board.gov/adaag/html/adaag.htm#4.17 for more specific information about accessibility requirements.