Hi there... our family will be flying from HK to PEK and stay in Beijing for 9 days for tour visit.

Yes, in T3, the exact locations are East/West of public space of Arrival Hall at 2F.
For one piece of luggage, the fare is CNY 30-100 per day.
When you paying the money, the staff will ask you about your name and contact information. Then you are given to a register number. You can use this register number to recollect your luggage.