Replacing fuel tank sending unit

i have never changed a fuel sending unit and have the following questions for all you pros at forabodiesonly.
1 Are there any unusual tool required?
2 What are the possible pitfalls associated with a rusty old unit being removed?
3 How is the new unit sealed to prevent leakage, gasket, o-rings, etc?
4 How do you clean the rust away from the opening if necessary without causing a spark?
5 Can you ground the unit to the frame as well as the gas line?

Thanks