Does lactose helps stimulate bowel movements to expel waste from the colon?

It is just simple osmosis... It draws water out...

That's not what usually happens where I'm from. Lactose is split into its 2 component monosaccarides and these are absorbed by the body and used as an energy source.

Try lactulose

http://en.wikipedia.org/wiki/Lactulose

Lactose is split into glucose and galactose which can be used normally as carbon sources.

If it is not metabolized (as in those with lactose intolerance) the lactose stimulates bacterial growth in the bowels with rather negative effects.

As far as I know lactose is only produced by female mammals to feed their young. That is its function. Bowels generally work just fine without it (except in the case of young mammals).

Also lactose intolerance is rare where I live (in the UK) so I stand by my assertion.