To be an actuary, you first of all get a degree (generally) in a numerate discipline (I'm sure engineering would be alright), actuarial science is apparently actually frowned upon by some employers, a friend at E&Y told me that they'd only recently begun accepting them again in the last couple of years, but they prefer if you learn it properly through experience than completely theoretically as you would in Uni.
Depends on you for how long you get qualified, it can take typically 3-6 years following graduation, depending on how well you do in the exams and if you pass them all quickly. You'll be working whilst you do them and get payrises as you go along, typically.