I wouldn't like to comment on salarys'. Other posts are suggesting a lower salary than permanent staff. Who knows, I'm sure it won't be great though as it's an employers market at the moment!!!!
There are lots of differnet contracts ie increments etc, so most FO's/SFO's are on different wages, but somewhere near £40k. As for time to command, I would suggest that is upto the individual and their abilities. Have seen guys come in after 2 years up-grade, so the scope isd there!
Good Luck