Panasonic 14-140 - switching to 14-45 - aperture and AF noise?

[GarageBoy]

I never use the long end of my 14-140 and was wondering how bad it would be if I switched to the much lighter 14-45? (AF speed and noise, aperture?)
Thanks!

ALSO: what does stepless aperture mean on the 14-140? (obviously, the lens isn't constant aperture, so what does this "feature" do?)