You would require a tall faucet anywhere from 12" - 13" height.
Spout reach, the distance from the center of the faucet body to the aerator, is an important consideration. Make certain that the spout reach will be sufficient to work with the existing vessel sink.
My under mount faucet has an opening in the back of it. What is the opening for?
The opening in the back of the faucet is used during the pull-up drain installation (the included metal rod gets inserted into the opening to operate the opening and closing of the pull-up drain). Considering that most faucets and drains are sold separately, always refer to the model of the sink as well as the faucet when considering purchase options.