nissan controls

Am getting involved with a friends mess until he can get the beast of a house boat towed back up to TAMPA. Right now it is in my yard. Currently has a 99, 90 PLUS NISSAN 2 stroke with a 25 in. shaft extension. Currenty mounted on a jack plate, corroded in the full up position, still just manages to keep the power head above the water as the port pontoon stern is only 2 to 3 ins. out of the water. Have to do further investigating but it appears the house boat only needs a motor with a 15 in. shaft.
Guess I am getting off the subject. Question is, will a new NISSAN match up to his controls and wire harness on his 99 2 stroke? Is a TOHATSU the same thing as a NISSAN 2 stroke? Is it a simple matter to remove the leg extension if we can get it apart after 5 yrs in salt water? Boat is a LIL HOBO, belongs in a fresh water lake. What a mess! regards FRED