While you still want to be a smart traveler (travel in groups, don’t flash large sums of money, don’t leave expensive items in plain view in your rental car), you should travel to Morocco knowing that you are going to a reasonably safe area. There are police on active patrol about every 100 metres in Agadir, including the beach, and this appears to be an effective deterrant. While you will be bothered by people on the street in the touristy areas, they are usually more annoying than anything else. Violent crime is especially rare. Most American cities have much more violent crime.
As for the tap water, do not drink it in your hotel. Although fortunately brushing teeth and rinsing a toothbrush should not harm, drinking it might indeed give you an upset stomach.
The only real food danger is in the form of local dairy products and undercooked meat. You don’t need to be on Malaria pills, and yellow fever is not a concern. You might want to update your Hepatitis shot before you leave just to be safe.
So remember to travel smart, but don’t forget to enjoy yourself. You are in a beautiful country, and so go out and explore it! Most of the Morrocans are quite able to speak French, but English is not so easily understood. So, in order to make it easier all round, brush up on French. Even a few friendly greetings like “salut, ca va” and “non merci” will be helpful to you, whether in the street, in a taxi, or in a hotel