If you came across two task forces in the same mission, then you were fortunate. That is an embarrassment of wealth from my experience.
As for the merchant men- sometimes you find them, sometimes you don't- they are generally out there, but finding them can be an elusive task. Try patrolling near the intersect points of trade routes.
If you get bored in looking along the trade routes and are feeling lucky- hang out around a harbor entrance... or just go right on in close and see how that works out for you. Dangerous, but productive.
