Congrats on your first boat and that is like jumping off a bicycle and jumping into a Ferrari. The proper oils and maintenance info is easy to get. Go to your local Merc dealer with the engine serial number and purchase the original operators manual. I also recommend, if this boat is coming from an individual, then ask him to take it out for a ride. Ask to watch him as he prepares the boat, launches it and when he recovers it back on the trailer. Go enjoy the ride. Have him point out how he gets it up on plane, how he uses its jackplate and trim ( if there is one).
Now there are some things to look at since you are just buying it. Have the batteries tested and replaced, right up front if needed. That boat will have a 24 or 36 volt trolling motor. It may have an on board battery charger. This means 2 or 3 trolling motor batteries.
The outboard motor will recharge the separate "starting" battery which is also used to run livewell, light etc.
If the boat does not have an onboard charger, you may want to add it, it probably does though.
Here is a part of my routine.
You will want to wipe down the boat after use, I do mine right in the ramps parking lot. I like to remove the plug and get out any water that may be in the bilge ( mostly from waves) and I store the plug in the same location every time. I also empty any water in the livewells.
This is important too
Once home my trolling motor is unplugged or turned off and the batteries are immediately recharged. This will give the batteries their longest life. My batteries are group 30 AGM batteries that cost close to $200 each, but I am on year 7 on them.
This recharging immediately is important.
Engine maintenance annually includes a new water pump impeller and a change of the lower unit oil. The impeller change is more important to me, since I fish salty brackish water and that can cause it to harden. When I ran freshwater lakes I only did it maybe every 3 years. I will grease every fitting once a year and do a total under hood inspection as well.
I do not have one, but your engine has a fuel filter. Replace it.
There is one more thing I would do before I ran the boat much. I would replace the entire fuel line and primer bulb, from tank to engine. This is a cheap solution to avoid a much more expensive repair later. The ethanol fuels we are forced to run these days are tearing up the inside of fuel lines. If yours goes bad enough to cause a performance problem, then the entire fuel system including electric fuel pump, float, and even injectors can be compromised. I just did this on my 2010 boat this past summer. I did not have a problem yet. It only cost about $60 to avoid potentially a several thousand dollar bill. I saw a few that this happened to and the entire line just disintegrated.
Trailer maintenance could include a wash down after use, if you run salty brackish water. Regular maintenance should include an occasional recheck of the tire pressures, and a quick torque check of on the lug nuts, bolts for the springs, any bolts up on the trailer tongue, like for a swing away tongue and the coupler. Check brake fluid level occasionally.
You need to find out what type of hubs and axle you have, The old system was a solid axle and Bearing Buddies, this required only an occasional pump of fresh grease. The next upgrade includes a drilled axle where you pump the grease into the fitting, it goes through the axle and fills from the back to the front. With this design all one has to do is pump in a tube full of grease and all of the old is replaced by the new. Lastly, the latest is an oil filled hub and that I am not sure how you maintain. Check with your dealer.
There are lots of other things to learn and you will over time. If you run into new questions you are welcome to pm me and I will try to help you more. Enjoy the new boat! Triton made a nice rig!