[susan53]

1. It depends on the context. You interpret which meaning is intended (often affected by vs dependent on) depending on what else is said. So eg you should be able to work out which is which in the following :

a) We've put in a recommendation that workers should be allowed to cut their lunch break to 30 minutes and then go home 30 minutes earlier. Most people seem to like the idea but it's subject to the boss's approval.

b) My mother was subject to migraines all her life. She'd have these terrific headaches which would last up to 24 hours.

2. No. As I said - they may be corrected. It's a possibility, not a probability.