No it's not mandatory for the company to deduct 10% TDS. If you declare your section 80C investments in advance, the TDS deductions will come down drastically. The best avenue to invest your money in a regular fashion is ELSS also known as tax saving mutual funds. Some good ones are Canara Robeco tax saver, Fidelity and HDFC tax saver.
Form 16A is provided to you by banks when TDS is deducted on your deposits. It is also provided by many employers when you are not a full time employee but on contract. Regular employees get form 16.