If you have an M-Audio device (or any other device) that has native ASIO drivers, you should not have ASIO4All. Delete ASIO4All from your computer. It will interfere with the operation of ASIO.
Stereo inputs for many devices will often be listed as 1, 3, 5, etc., 1 being the stereo pair 1 and 2, 3 being stereo pair 3 and 4...
Without knowing what synths or effects you're using, it's hard to guess why you're getting mono outputs. There may be a selection in the synth/effect insert menu or GUI for mono or stereo output.