Once the wort has been topped off and aerated, it is time to pitch the yeast. Pitching is the term brewers use for adding yeast to wort. Once a beer has been pitched, it is considered beer.
Some packets of yeast will suggest rehydrating (making the dry yeast liquid) before pitching. We have found that rehydrating the yeast introduces the possibility of contamination, and that simply sprinkling the yeast on top reduces this risk and works just as well.
Bucket lids have a tenancy to be difficult to remove. One trick we have found is to start at one point and lift it slightly, and inch your way around the fermenter. Once you have made a full rotation, it should be much easier to lift off.
Similarly, securing the lid to the bucket is easiest you push down on one spot, and work your way around the fermenter until you have made a full rotation.
Airlocks can be filled with either cleaner or vodka. Water is not advisable, as it will not neutralize any contamination that manages to find its way into the airlock. The liquid level in the airlock can change and cause some of the liquid to go back into the fermenter which can infect your batch if you do not use cleaner or vodka.
The red cap on bubbler type airlocks does not interfere with the mechanism of the airlock, and can be left on. This will act as a barrier to prevent any dust from reaching the liquid in the airlock.