Is it true that Buddhism are taught to be tolerant of other opinions, beliefs, customs or behaviour different from their own?

Yes, Buddhists are taught to be broadminded but not to believe in anything easily before investigation or proper consideration. Moreover, Buddhists are taught to diffuse the Four Divine States of Mind: loving-kindness, compassion, sympathetic joy and equanimity towards all sentient beings who may be of different nationalities, religions or environments.