100w mobile phone can not be charged with 40w fast charge, because the rated power and rated current of 100w mobile phone are larger than the rated power and output current of 40w fast charge, when the small current of 40w fast charge to 100w mobile phone, it will cause the mobile phone to charge slowly or not charged, so you should choose the fast charge that matches the 100w mobile phone.
Yes, but the charging speed will be slow.
Yes, the mobile phone charger is universal, change a corresponding data line can be