You are permitted one piece of hand luggage, weighing 23 kilos or less, that can fit into the overhead bin, as well as an item such as a laptop or handbag. You are allowed to check in one bag weighing up to 23kg.
It depends who you are flying with and what you are willing to pay. You should check your flight company's information for that information. Generally, for carry on items you are typically allowed one piece of luggage and/or a purse.
This would depend on the type of flight. First class flights for check in is 50 kls while economy class in 30 kls. This is only applicable for all flights except for US/Canada and Brazil. Australia flights also differ.