Getting back from Venus is as easy as launching from Earth: i.e., completely doable with present-day technology. The only issue is getting it there to begin with, but that's not really hard, though we'd probably need to launch several rockets here on Earth, and assemble stuff in space, to get all the mass needed for a single launch on Venus. Landing stuff on this hypothetical Venus would be much easier than on Mars, since this Venus has an atmosphere, and Mars only has an "atmosphere" (one that's 1/200 the pressure of Earth's, not really much of one), so we'd be able to use aerobraking, parachutes, etc. In fact, landing stuff on today's Venus is pretty easy, and the Soviets were doing this ages ago; the only problem is that landers didn't last long because of the heat and corrosive atmosphere.