For the duration of the fight, creatures in the immediate area will not be visible to you (but they may still attack you if they wander too close). Keep in mind that other players will still be able to see you and attack you if you are eligible for player vs. player (PVP). Other players will also be able to view your pet battle in real time, including the pets involved as well as their health as the match progresses.
To gain gold in World of Warcraft, you will primarily be grinding professions which are fantastic for receiving rewards. Mining is an example of a great profession at an early-game level. While Herbalism is actually the best gathering profession, the issue is it uses consumables which can make the profession rather costly, with the investment required.