Yeah, for everyone who's done a few briskets, there seems to be their favorite smoke wood(s) and favorite method to bring it to the table...I'm no different. But for those who are just getting started, I like to recommend the easiest no-fuss methods that give a reasonably good eating brisket...you were already underway with a good, simple method. As you explore the possibilities for later smokes, you'll find the merits in using more complex methods, but I find it better to start simple so you have something to look back on to gauge any changes you make against the results of previously used methods.
Anyway, the sugar should be fine for you today...maybe 10hr or so smoke time...if it were a lightly trimmed 18lb packer, you'd be looking at possibly 24 hours...that's a whole new animal for carmelization of the sugar. The use of sugar on beef, for most, doesn't really fit quite right in the flavor profile, but for pork, a sweeter flavor works really well...that, of course, is a personal choice/preference, and even as an experiment, there's nothing wrong with it at all. I won't bash anyone for using sugar on beef just because I don't. Many are tempted to load up their dry rub for a 9lb pork butt with 40-50% sugars, by volume...risky proposition for a 18-24hr smoke on open grates...for some it probably works fine...depends on the smoker and chamber temps, smoke chamber humidity, etc. If conditions are right for it, no issues...if they are wrong, then it becomes one of those less desirable experiences we learn from.
Sugar will contribute to bark, so yes, it will help you with that. Speaking of bark, if you desire a firm to crisp bark, you can use a method similar to the 3-2-1/2-2-1 for pork ribs by going back to open grates when the brisket is approaching your desired finished temp. An hour or less on open grates, depending on how firm you want the bark, should be sufficient to set it up nicely. This shorter ride back on open grates shouldn't be long enough to cause the interior of the meat to dry out. Use caution when handling (insulated silicon mitts or a large meat tine to lift will help), so as to avoid dragging/scrapping the unset bark off of the meat...during handling you will be able to determine to some degree how tender the brisket is by feel, as well.