Motorcycle shaking?

For questions 1 & 2, get the serial number of your bike and check with Yamaha to get an Operator's Manual. All basic maintenance and fluid usage will be noted there.

Question 3: Technically yes, but it wouldn't make much of a difference on your bike. With a straight or open pipe, it reduces the backflow to the engine which over the long haul, lowers efficiency.

Question 4: Just keep debris out of the chain/sprocket. You should probably have a technician do it for you, but you can clean and lubricate it yourself if you know how. You can probably find Youtube videos of this.

Question 5: Are you traveling at top speed for a long time? Your bike is actually more of a scooter than a motorcycle, and they aren't designed to sustain max revs for very long.

Question 6: Yes, they are designed as a commuter bike.

1, 10W40 semi-synthetic motorcycle oil is usually the universal recommend. However, checking in your manual should show the recommended oil what the manufactures state.

2, I change mine every 3000 miles or once a year, which ever comes first.

3, No, it will just change the engine sound. No real performance gains.

4, Clean them every 300 miles or so, with wire wool etc. Oil the chain at the same time, after cleaning.

5, Are you sure that your tyres are OK? Wheels are tight and aligned correctly? Riding it at top speed (IF that's what you do) is bad for long periods of time.

6, Decent, more of a city commuter bike though. It depends on what roads you need to use though, high speed road or low speed roads?