Drop bars give you more handhold positions (helps alleviate wrist soreness on longer rides) and let's you get down lower and more aerodynamic. Neither is important for a short commute but if you end up going on longer rides it might make sense. Most bikes that are advertised for commuting have flat bars, not drop bars.

There's no specific brand that has low gears, it's the type of bike that will determine that. Racing bikes usually don't have low gears, mountain bikes and touring bikes do. As a rule of thumb I'd want the smallest front sprocket to be smaller than the largest rear cog (sprocket). The smaller the front sprocket is in relation to the rear cog, the lower the gear (and vice-versa).