You don't have to use preceding 0s when specifying an ID. You can just use \v[61] and $game_variables[61]. I don't know if that'll fix the problem though.
As for your other problems, this should fix it. Follow the instructions, and paste this above Main.
# To not forget a skill upon class change, put either the tags:
# \DON'T FORGET
# \DONT FORGET
# case insensetive.
class RPG::Skill
def dont_forget?
return @dont_forget if !@dont_forget.nil?
@dont_forget = self.note[/\\DON'?T FORGET/i]
end
end
class Game_Interpreter
def command_321
actor = $game_actors[@params[0]]
if actor != nil and $data_classes[@params[1]] != nil
for i in actor.class.learnings
s = $data_skills[i.skill_id]
actor.forget_skill(i.skill_id) unless s.dont_forget?
end
end
actor = $game_actors[@params[0]]
if actor != nil and $data_classes[@params[1]] != nil
actor.class_id = @params[1]
for i in actor.class.learnings
actor.learn_skill(i.skill_id) unless i.level > actor.level
end
end
return true
end
end