Does kidney cancer usually cause many symptoms?

It depends. It depends on the extend of disease. Patients with kidney cancer can present with a range of symptoms; unfortunately, many patients are without symptoms until the disease is advanced.Clinical manifestation may include- blood in the urine, weakness, low grade fever, decreased apetite, abdominal /pelvic discomfort , etc.
No. This kind of cancer is typically found by chance, unless you start bleeding from it. Typically the urine will be coca cola colored.