In the piano roll editor you can leave the grid on and press Alt after clicking a note to drag it off of the grid.
You can get your audio clips and MIDI notes to groove right by turning off the grid when writing funky sections.
Ableton Live comes with lots of built-in instruments and effects. Both the Impulse drum machine and Ping-Pong Delay come bundled with Live. However, these instruments and effects are not VST plugins.