Welcome to the forum
For 1 Always always always change the filter. And always always always make sure the rubber gasket comes off when you take off the old filter. Take some new oil and smear it around the new filters gasket.
2 look in the manual i forget what page, but it has the Manufacturer’s maintenance plan near the back.
3 that is up to you. Just 1 be sure its the right size and 2 its not one of those cheapy fram filters. It should cost you 3-7 bucks. Just do a little research on filters.
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