Usually 4-6 wks. But this question is always better answered by the surgeon that operated on your chest. They may have a very good reason to allow you back sooner, or keep you at rest longer. I can promise you they will not mind you asking them!
Depends. It depends on what a patient does for a living, and what type of surgery they had. If someone had vats, then they should not lift anything > than 20lbs for 1 month. If they had a thoracotomy or "big cut" then no lifting > 20lbs for 2 months. If a patient's work requires driving or operating heavy machinery, then return after they are off narcotics. Otherwise return to work when comfortable.