WASHINGTON, Aug. 29 - With a newly robust endowment burning holes in its not-for-profit pockets, National Public Radio is in the midst of a major expansion. But NPR's ambition has stirred anxiety within the public radio system over how to preserve the character and financial viability of local stations in the ever larger shadow of the national production service they created more than 30 years ago as a modest support operation. NPR, a member organization governed in part by local stations, is pumping $15 million into its news division over the next three years, using interest from a recent bequest...