Spaceception

Not possible. Even Einstein predicted that wormholes might be unstable. You're describing using them as a conduit to transport matter that's in the form of a gas. Gas needs pressure exerted on it. Think of a spray can - you have the product AND an amount of propellant gas to force the product out of the can. The can itself creates a high pressure environment and as soon as you press the nozzle button, it creates an escape conduit from a high pressure area to a low pressure one (outside the can is considered low pressure). You'd have to create the same thing on Venus - with a propellant.

If you are serious about terraforming Mars, you'd be best off to mine the carbon dioxide ice out of the polar caps and reintroduce it to the atmosphere. But even then, it would be a crap-shoot since Mars has been leaking atmosphere for the last few million years. You'd have to find a way to increase the planet's rotation to even create a scenario to where the gasses would be held in its atmosphere by gravity (even the Earth has some atmospheric dissipation into space). The other thing to do would be to increase the mass of Mars, which actually theoretically could be done, if you were to harvest ice comets and send them down to refill Mars' oceans - after all, it is science fiction, right?

With Mars as it is now, at best, you would have to be continually replenishing its atmosphere. 

@adsii1970 I second this ^ Though in my opinion a great way to terraform Mars would be to take a small ice Moon from the outer solar system, Cut it into small asteroid size chunks, Then send them hurling into Mars on an atmosphere grazing trajectory so they would evaporate mid-aerobrake and thus thicken the atmosphere without damaging the surface. Also. If we're talking far future, Then it could be possible to drill a hole all the way to Mars' core  and insert a small chunk of Neutron Star in there, A mountain sized chunk of Neutronium might be enough to significantly increase the planet's gravity.

@daniel l.: The major problem with what you propose (the whole drill to the core and insert neutron star piece) is the technology to drill that far into a planet would be finding a way for the drill bit to survive the high-iron content rock, the pressures (the further you drill underground, the greater pressure is exerted on the hardware), and that's just the drilling aspect! Most astronomers and exo-geologists are unsure what lies under Mars' crust - they are not even sure if Mars still has a remnant molten core - and if it did, drilling into it could literally collapse the planet.

Then there's the aspect of the part of the neutron star - there are none in our stellar neighborhood. The second problem is even if it were, what would be the impact of having a Mars with that much mass - even a golf-ball sized particle could make Mars so heavy and have such a deep gravity well that not only would it lose at least one of its moons, it could possibly disrupt the Asteroid Belt...  Remember, Mars is closer to the Asteroid Belt than Jupiter. Right now, Jupiter is what keeps it in check...

Another problem is with that much mass, how would you ever be able to handle it? How would you get it to the surface of Mars and to the exact coordinates of your bore hole to the core? The heavier the mass, the more hard it is to align it to a precise target (a bore hole would be no bigger than about 15 to 20 cm, using standard drilling technology AND the size of the hole needed for a golf-ball size fragment).

The most practical and realistic approach would be to harvest water-ice comets and let them impact the surface, preferably in one of the old ocean basins. We already know those former ocean basins and their depths, so if you nudge the comets into impact into those areas - they should not cause any real harm to potential habitation zones in higher elevations. The difference is not only mass, but it doesn't require as precise of a landing zone. Consider having a target zone of 7 to 60 Km versus 20 cm - it simply makes more sense.

Fragmentation of the comet wouldn't be necessary. Up to 1/4th of the mass would probably burn up during reentry, adding water vapor to the atmosphere as it reenters...