I have just had to replace my spark plugs at 130 hours. Apparently this is about the most one can expect from a set of plugs. They were pretty worn out and had started to cause the engine to stall at idle.
It is worth removing all the bolts from the gearcase one at a time then greasing them with triple guard before refitting, do this every 6 months or at least yearly. This way when the time comes it wont be an angle grinder job
It is recommended that the powerhead is rinsed off with a low pressure hose after use in salt water, just take of the cowling and rinse it down, just don't aim the hose into the air intake. I did not do this in the first year of use and my sounder was chucking water up at the side of the engine and there were definate signs of corrosion on the brass oil recirculation fittings at the bottom of the engine.
Nothing wrong with plugging in the dealer software you must have located somewhere on the web
it won't have any affect on your warranty.
Every year take of the lower cowls and corrosion guard any bolts you can see likewise give the whole powerhead a blast with the corrosion guard.
Other than that just keep your fuel filters clean and dont put shit fuel in it as the injectors are sensitive to water etc and long term use of shit fuel (E10) will just end in tears.