A Singular Destiny is Keith's own story, not an epilogue to mine. It carries the overall political situation of the 24th-century Federation forward after the events of the trilogy.
As to your second query, you should, in theory, be able to just pick up any Star Trek book and read without needing to read any other. But if you aren't at least familiar with what happens in Destiny, books set after it in the continuity might feel a tad … unfamiliar.
As to your second query, you should, in theory, be able to just pick up any Star Trek book and read without needing to read any other. But if you aren't at least familiar with what happens in Destiny, books set after it in the continuity might feel a tad … unfamiliar.