That depends solely on the size of the industrial you want. The barbell spans the space and therefore needs to be sized according to the ear of the client and the desired look one is going for.
Cartilage piercings can remain sore and tender for up to 2 weeks. They take longer to heal than other piercings; the healing time for cartilage piercings is slow. For any swelling and/or discomfort,...
You should always clean it. Clean it 2-3 times a day for about 2 months then after that once a day with rinsing in the tub/shower is good. Industrials can be unpredictable so you may have to clean it...
Bathing isn't a problem. Just be careful when you're washing your hair so as not to hit it. If you put water on it, make sure that its clean (not what you're sitting in). Shower would be better than...
2-3 months before you can change the bar. Industrials are really tricky to heal though. People have them for years and they still act up. Just get a bar that isn't too long or too short to prevent...