By weekly out of class workload do you mean self-study and homework or labs? In my university labs aren't included into credit hours; so a class of 3 hours of lecture + 3 hours of lab a week is still 3 credits.
Each credit hour corresponds to 50 minutes of lecture per week with an associated typical weekly out-of-class workload of 2-3 hours. For example, a 3 credit hour class would have a total of 150 minutes of lecture per week with 6-9 hours of out of class work.
Yes, that includes homework, assignments or whatever.
Lab may be included as 1 semester credit hour which would be 3 hours/week.