Please use a glider specific log book to record your glider flying. As well as helping your instructors, you too will find it helpful in various practical ways to keep this form of flying type logged separately.
FAA Knowledge Test
Power pilots (Private or higher rating) do not need to take an additional FAA Knowledge Test. However, be prepared to answer verbal questions from the Examiner about all aspects of gliders and soaring.
Power pilots (Private or above rating) can go solo with relatively little additional training (and fewer endorsements) and once solo are not subject to the same level of continuing instruction as student pilots. Power pilots are NOT students: they are rated pilots seeking an additional rating (glider). SCOH does however strongly advocate taking the Practical Test without unnecessary delay – one advantage of the add-on Private/Commercial Glider Rating is being allowed to take passengers.
Many prudent and experienced glider pilots have recorded their thoughts and wisdom in textbooks that make it easy for us to learn from the mistakes of others. Some textbooks have been written specifically for the power pilot transitioning from airplanes to glider.