It varies. If the edema is in the cornea, lens or retina it can severely affect the vision. Examples would be cornea edema after cataract or lasik surgery, lens edema due to osmotic shifts in aqueous fluid and glucose in a diabetic patient or retina edema following any eye surgery or in diabetic retinopathy. Hemorrhage is a minor inconvenience if it's on the outside of the eye but can affect vision inside.
Depends. Edema and bleeding at the back of the eye can alter the vision from a minor to a major degree depending upon the location. If close to central vision (the macula) it can be substantial. If the bleeding fills the back of the eye it also is substantial. Any bleeding or edema at the back of the eye needs evaluation and treatment as soon as possible by your ophthalmolgist.