You might have to bend the sender's float arm. Measure how far the float drop is and compare it to the depth of the tank.
Yup!
To me, having a accurate gauge when you are running low in fuel is very important. I would drain the tank, then add just 4 gallons (assuming your tank is 16 gallons), install the sending unit and then check to see how close to 1/4 tank reading you get. If off a little, tweak the sending unit's arm as Gord mentions. And yes, those floats can develop a leak or two.
