If you are highly organized and get your routine down its potentially profitable. (Although it depends on how much you are looking to earn too). Travel time is not reimbursed per say. There is mileage paid at a rate that's a little lower than usual but only if you travel over 40 miles. Adding that much travel time, as you mentioned, eats away at the profitability factor so closer is better. And they don't necessarily assign cases that are near one another geographically so that can decrease ones efficiency.
No- there is a minimum number to complete that is unrealistic. You drive all the time and little to no mileage reimbursement. The assessments take around 4 hours to complete. The pay is not worth it.