You can. Yes you can walk and jog unless it is uncomfortable. If you are having symptoms or the hernia is large you will need to have it surgically repaired. You should absolutely not do any heavy lifting greater than 10 lbs. Nor any abdominal exercises before and for 6 weeks after repair.
Absolutely. There are no physical restrictions with any hernia, except for the amount of discomfort one does or does not have. You may lift, work hard, even work out. However, in the time immediately after a repair, your surgeon will give you temporary restrictions. Good luck.
Yes. Umbilical hernias are common and are often asymptomatic if it causes pain or is getting bigger see a general surgeon and discuss surgical repair exercise over time tends to make hernias enlarge and can be uncomfortable.
Only if no pain. A lot depends on how big your hernia is, but if it is not causing any pain, nausea, vomiting, or distention, it is probably ok. Also, if there is any discoloration of skin over the hernia, it is time for surgical repair.