I use this for calculating several factors in my beer, others will say they use Brewsmith, but it is not ported to Linux yet.
Brown sugar will change the flavor of the finished beer. I've used flaked corn, corn sugar (dextrose) and table sugar for added alcohol when needed. Unless you are doing an Imperial India Pale Ale (or other gigantic style beer), you probably will not bump into the alcohol tolerance for the yeast.
If you are not growing your own 6th generation barley and hops, you're not *really* homebrewing.
Fermenting: Real Ale, Extract Lager (with WLP830), India Pale Ale
Drinking: Pale Ale from the keg