Is the James Webb Space Telescope a (more or less) secure program at
this point? Has the design been finalized? Has construction begun?

I'm guessing that it was intended from the start to go up on an
expendable launch vehicle, since I've heard no mention of any impact
on the program due to the shuttle's retirement. What type of orbit
will it be in? Also, what is its expected lifespan?

It sounds like Hubble's rate sensing gyroscopes may be the determining
factor in its remaining life. Obviously the new space telescope will
need something more reliable, since it's not designed for on-orbit
servicing. Would ring laser or fiber optic gyros provide more life
than the Hubble's mechanical gyros?

Sorry for all the questions, but I'd appreciate any info y'all may
have!