If level 0 skills have to be practiced in person(page 16), why was he allowed to upgrade Finger of Nirvana from lv.0-lv.1 with 3 points(refer to chapter 6 page 8)???
Level 0 skills don't have to be practiced in person. What needs to be practiced in person is the skill up to level 0 (introductory-level or entry-level).
The finger of nirvana is different because it was conferred to the MC instantly from the tablet. So he didn't have to learn the basics.