who lead perl5 develop?

The Perl 5 Pumpking, currently Alberto Simões Ricardo Signes. (thanks JavaFan for correcting that).

who determine if add X Y feature into perl5?

Well, you need three ingredients for that: somebody who implements it (including documentation and tests), the approval of a big part of p5p, and the approval of the pumpking.

Jesse Vincent (the previous pumpking) has given some great talks on his future plans for Perl 5. Your search engine of choice will find them.

There's also a perltodo file.