The Forney 140 MIG uses an aluminum wound transformer.
Yes, although a 3/4″ cut will require patience and significant cleanup with this machine.
The ground cable for the Forney 700 P is flexible.
The Forney 700 P is 40A and will cut thicker material faster.
The Forney 250P+ (ITEM# 317) does not have a problem with dry air. We’ve actually added driers to the newer models as moisture in the air can cause a short in the torch.