Something to keep in mind is that the dealer and auto mechanics will charge you the "book" value for repairs. The book listed the changing of coils and spark plugs at an hour and a half and talks about having to remove the upper intake manifold, which means the removal of lower intake and air flow system... WRONG! The coils and plugs are accessible right from site if you have a wrench with a simple adaptor. It took maybe 30 minutes going slowly to make sure not to break anything.
Single platinum NGK OEM plugs are great and cost 5$. The doubles are 18$ and the iridium are about 25$. You won't notice the difference if you don't do high RPMs and race-style driving. Gas mileage increase is maybe 3% (theoretically, though unlikely)... Not worth it really.
O2 sensors are not too bad to replace. The harness is a bit of a pain though. MAF sensor is also really easy to change so don't let them fool you with ridiculous time estimates. Fuel filter only needs servicing if you treated your car badly.
NEVER USE ANYTHING BUT PREMIUM FUEL!! Just don't do it. The book says use 91 octane (93 octane in the states I believe) so use that. You save only about 100-200$ PER YEAR and can cause serious damage to your sensors, catalytic converters and entire injection system. No matter how many "experts" tell you otherwise, don't listen. Knock sensors and all the other sensors adjust your car to perform at the best possible conditions under the circumstances. You could likely do lots of mileage without a problem with 85 gas but why run the risk? 1 02 sensor = 130$. 1 coil is 80$ or 68$. CC is 600$+. Not worth it. Plus, the car will simply perform better and get slightly better mileage. So you actually likely save nothing in the end.
I have lots of pictures and advice for changing parts on this car so don't be shy in asking for any help.