Skip the secondary, it's not necessary.
You are probably going to end up at rougly 3.5% ABV as it stands. Adding 2lb of sugar pushes your gravity to 1.05 and you end up at rougly 5.2% ABV. This will change the taste to be on the drier side of things. It's up to you. I am personally fine with drier beers and I'd rather up the alcohol. Any more than this amount will likely be too dry though.
If you are going to add the sugar, you can add it to your fermenter. It's fine to open the fermenter during fermentation as it's producing plenty of co2 and the yeast is active enough they will devour all the oxygen. Boil some water, add sugar, stir. Let it cool to roughly the same temperature as your wort is and pour it in with as little aeration as possible.
You can also just add more malt extract, that costs a bit more though.