It takes a day. With emphasis on eyes.
A day with the whole shebang!
for example: hearing test is done in a sound proof testing booth.
visual field test using humphrey field analyzer, eye pressure and fundus photo tests.
It's rather expanded but nothing that a normal person would fail.
Limitations are the same. depand on your age and condition.
If you have a class I, I would not worry too much.
I think China, Taiwan, Japan and Korea Class one is bit more arduous then other Class one. Hong Kong and Singapore is easy and fair. Like the rest of the world.