I think you got the wrong reading on your grav. after boil. Your goal is to have it higher before the fermentation and lower after fermentation. Higher your gravity after boil (just before you seal the cap on your fermenter) the more alcochol is in the beer. If your gravity reading was between "1013 and 1016" then I think you forgot to add the malt/sugars to your batch because that is around what your finishing gravity should be. Sorry if this is something you knew and I just read it wrong but I was a little worried for you.
On to your question; You can add "table sugar" to your brewing but only in small amounts due to off flavors being produced. I recommend if you can't resist adding more sugar to your brew to do it before your fermentation has started and use candy sugar or more malt extract. As stated already by iparks81, you really didn't do anything to your brew adding the sugar at that stage and at that quantity.
On to the yeast topic. I have learned to not go cheap on your yeast because that is what really makes your beer. I started out with my first batch using dry yeast and decided to try liquid yeast; the "Smack Pack" is so simple and turns out AMAZINGLY. All you do is take it out of the fridge, smack it to break the pouch within the pouch, let it set at room temp. for a few hours (smack it as you start your brew process if your doing a partial grain or malt extract process and it will be ready why the time you need to add it). You will know its ready because the pouch will blow up like a balloon; tear it open and add to your fermentation bucket.
I've never used the yeast booster that I know of, so sorry, I got nothing on that.
PS, start looking for kegging stuff to make your own kegerator/keezer now if your doing bottles because you will soon say screw this bottling stuff! It is far cheaper to build your own kezzer/kegerator than you think. I started otu with bottles and am now building my own kegerator from items I'm getting for cheap off of ebay/craigslist and local bottling companies (corny kegs for cheap... used but in perfect shape with new seals I got three for $10 each!).
Cheers and relax, it always turns out right if you remember to sanitize everything after the boil point.