JW Space Telescope is designed for a 5-10 year mission duration. Seeing as Hubble and other space missions have paved the way for JWST for reliability issues, It even has zero friction gyro's with 100+ years mean time before faliure. Is it reasonable to think that JWST can last longer than hubble?

JWST will orbit a Lagrange point in earth's shadow and will be 4 times further than the moon, around 10 days of travel away, and NASA states that JWST won't be serviceable. Why?

Why are JWST's fuel limitations so short? Are there no provisions for refuelling? How many gallons of dinitrogen tetroxide (N2O4) as oxidizer and hydrazine (N2H4) will it contain?

Surely NASA are secretly hoping for a 20 year mission?