What i would suggest is to buy a Factory Honda Service Manual , you can get one here
https://www.crfsonly.com/catalog/produc ... ts_id/3226 , or order one from your local Honda Dealer , it will show you everything you need to know about maintenance , and adjustments , and oil changes , suspension tuning and suspension service
On the suspension , if the guy was a fast rider , then the springs should be ok for your weight , as faster riders run stiffer springs generally , but i would reset the clickers out (counter clockwise) , what i would do is click them in till it just seats (clockwise) counting the clicks as you go (it will be at like 12 or so from all the way in most likely when you start) , then turn it out counting clicks till it stops (24 or so total) , then go right in the middle setting , and start with that (compression clickers only) , if it feels too stiff still , then click out 2 clicks at a time till you notice it getting softer , then keep going , riding each time over the same terrain , till it starts feeling stiff again , where it started to feel good and started to feel bad , is where you will most likely be comfortable , as you get faster or track ride , then you will stiffen accordingly , set your rider sag to between 100-110mm , depending on what feels best , if you think the bike is too tall then the 110 would be a good start
Now with all that said the forks are Air Forks , so you need to also check your air pressure before every ride , every day you ride , you need the special pump made for Air Forks
https://www.crfsonly.com/catalog/produc ... ts_id/4777 , you will want to be around 38-40 psi , maybe a few lbs lower , to make it more forgiving on the hits , the air pressure along with getting the clickers dialed should give you the ride your wanting , but remember , its a MX bike ,not a tral bike , so the suspension is going to be stiff , there is no way around it without getting it revalved
As far as frequency of oil/filter changes , if your using Petroleum oils , every 3-5 rides is good ,if your using Synthetic oil , then every 5-10 rides is fine , if the conditions are not dusty at all , you can go longer with synthetic , i usually change mine about every 10 rides with Amsoil or Maxima Synthetic , if i was using petroleum it would be every 3 rides oil and filter
Air filter check every ride , if it looks dirty (if its got brown on it , its dirty) then change/clean it , i would not go more than 2 rides on a filter without changing/cleaning no matter what the conditions unless it was pavement , its not worth the damage that can be done to the valves , I change mine every day i ride , each day a fresh filter , i use No-Toil Oil and Extreme filters , it ain't cheap , but after losing intake valves on 2 bikes i learned that the air filter is the life blood of your bike , don't keep it clean , and your engine wont be clean , and it will die young
) , and there is never a "stupid" question , only stupid mistakes from not asking questions .....