An industrial can't be created by connecting two pre-existing piercing holes, because the angles of the holes will not line up correctly to create proper balance. Balance is extremely important because stress on the cartilage can lead to infection and even permanent deformation of the ear. It takes a skilled artist to place a perfectly balanced industrial.
When pierced properly, an Industrial is a fun and attractive piercing and one of my personal favorites - the photo you see here is of my very own. The jewelry I wear is a standard Industrial bar, which is just an extra long straight barbell. There are also many other barbell varieties which include spirals and twists for a little extra pizazz.
The gauge size of each individual's industrial will depend greatly on the depth of the rim it will be penetrating on each size. Providing you've found an experienced piercer, their recommendation will be best, but the standard is typically 16 or 14 gauge. Proper length is also essential, which your artist will decide based on the chosen placement of the piercing.
With proper alignment, balance, and aftercare, and Industrial will heal in about 4-6 weeks, at which time you can opt to change your jewelry style. If you encounter any problems during healing, you'll probably need to wait an additional 2-4 weeks.