Yes, that should be a nice eng. Are present 9.9 is a limited 15hp. In the low hours it is best to vary the running speed. Salt water is a problem with everything. But proper preventative attendance will keep the engine in good shape.
Prices vary greatly.
Shop around is my best advice. Our outboards are really rather simple. The the Carb versions are basic in computer control. The large Carb'ed engines meet EPA 2006 and CARB 2008. The smaller engines do not meet CARB 2008.