OK I know nothing about Salt boats

Does anyone know the approximate amount of hours a 140 hp Evinrude could have on it before needed to be rebuilt?

What are the advantages and disadvantages of an outboard vs. an inboard outboard. Pertaining to...

Life expectancy
Maintenance
Reliability

Boat will be used almost every weekend in the salt and will not be moored, it will be trailered.

I am trying to decide what type of motor to go with. Currently I am looking at a 20' 1989 Glasply with a 140 hp Evinrude outboard.
_________________________
A.K.A
Lead Thrower