Yes, check out the Tohatsu. I have one on my San Juan and one on my dinghy, they are very reliable and fairly small as outboards go. Price is good and the quality is excellent. Both Mercury and Johnson get their small engines from the Tohatsu factory. They also sell the same engine as a Nissan for a little more money.
6hp should be fine as well, the boat will only go so fast regardless of how much power you put in it. The only advantage of a 9.9 is electric start but that adds weight and cost. Not sure you will need a longshaft for a boat with a well but the Tohatsu Sail-Pro is considered "ultra long". It also has an alternator to keep your batteries charged. The extra expense of a modern 4 stroke will pay off in having fewer problems as long as you maintain it. About the only time mine give me any trouble is when they get a little water in the carb. then all it takes is a screwdriver to drain the float bowl.
Good luck and enjoy your boat, also please look around the site to learn about your obligations as a newbie.