You would need to figure out how much air you are flowing through your current engine to determine if the cooler is large enough.

The Silicone Intakes site makes some reference that using a standard air to air intercooler that has been modified to have water running through the core then boost pressure running where the cooling air used to run is not so good. I don't know that is a problem other than taking up too much space.

If I did use a low cost air to water cooler, I'd tend to plumb the system so water drains from the cooler when the engine isn't running and make it a non pressurized system. I'd be concerned that a small leak from water to air would hydralock the engine when it was off.

Tubing size won't add to or take away from torque, it has to do with lag between the time the throttle is opened and pressure rises.

For the cooler in your post 14 , I'd run the other water connection on the other side of the cooler and a top to bottom flow ( or bottom to top as this would tend to keep the intercooler full of water.) . If both are on the same side the water will tend to take the shortest path.