The timetable in Japanese:
http://www.kusatsu-onsen.ne.jp/access/train01.htmlThe upper table shown the timetable in direction of Kusatsu. The lower table in the opposite direction.
The tables also include the schedules of the trains between Takasaki and Naganohara-Kusatsu-guchi.
草津温泉バスターミナル meand Kusatsu Onsen Bus Terminal
長野原草津口 means Naganohara-Kustau-guchi
One more question, what time do they normally serve breakfast in ryokan?
Normally between 7 and 9, but it depends on the ryokan.