It is "va" because the a in va represents he, she, and you (formal). He is going to the pool, so it is 'Mi padre va a la piscina con nosotros.'
Ana está cepillándose los dientes.
Meal time is usually at 3 but can be from anywhere 2-4 in the afternoon. Im not sure what you mean by "restaurant practices" but heres a website that has information of food customs.
https://www.enforex.com/culture/spanish-eating-customs.html
Se encaprichó con estudiar en el extranjero y ahora se ha disgustado porque no podrá hacerlo.
He set his mind on studying abroad and now he's upset because he wont be able to.
