Age on other planets
Neptune takes 164.8 Earth years to orbit the Sun, so it has completed exactly one orbit since its discovery in 1846, that anniversary fell in 2011. No human has ever been one Neptunian year old, and nobody ever will be. Mercury is the opposite extreme: a year there is 88 days, so a ten-year-old is already past forty.
A year is one orbit, and orbits vary enormously. Mercury takes 88 Earth days, Mars 687, and Neptune nearly 165 Earth years, so a 36-year-old is 149 on Mercury, 19 on Mars and one fifth of a year old on Neptune.
How to find your age elsewhere
Days are stranger than years. A day on Venus lasts 243 Earth days; longer than its 225-day year, so a Venusian day is longer than a Venusian year, and the Sun rises in the west because Venus rotates backwards. Mercury has a 3:2 resonance between its rotation and orbit, giving it a solar day of 176 Earth days, or two Mercurian years. Orbital periods are the tidy part of this comparison.
Questions
687 Earth days, or about 1.88 Earth years.
About 4.15 times your Earth age, since a Mercurian year is 88 days.
No. Neptune year is 164.8 Earth years, longer than any human lifespan.
Yes — 243 Earth days of rotation against a 225-day orbit.
A 248-year orbit, and it has been a dwarf planet rather than a planet since 2006.