I have made short silent video files using Poser, but please where can I find a package that can:

(0) Cut and join video files.

(1) Add sound effects.

(2) Change the size of a each frame in a video file, so that it matches another file which it is to be joined to.

(3) Make a voice audio file from a text file. (I have seen/heard on Youtube plenty of voice audio that sounds like output of such a package.)

(4) Change audio modes and video modes.

(5) Are there any good big downloadable libraries of sound effects? (To such a library, I could contribute a short sound file that I made with help from a mobile phone's camera :: a hobnailed boot footstep, and a series of them.)