Mmm. Well, if you notice my animations/images avoid caustics cause they eat-away rendering time. Most people don't use them unless it was a closeup of a glass - even then alot of time it is 'faked.' If not necessary - turn them off.

As for time - I've been doing graphics for 8 years interspersed with normal non-related work - it's really a hard measure. I'm obesessive in learning so I can spend 16 hours a day 7 days a week studying and working at images. For some people it comes quicker - for some it doesn't. It also helps if you know someone that can show you the basic prniciples.

As for costs - they can be very expensive. Most sites offer a free demo version to play with.