Yes, only «seus» goes with «você», and only «teus» goes with «tu». From what I understand, it depends from where you are in Brazil. Some Brazilians always use «você», some use both «tu» and «você», some use the «você» conjugations for «você». In Portugal, it is common to use both, «você» in more formal occasions.
You mean on «nós»? It is mandatory when it means "we" (subject pronoun). When it means "us," then you take off the accent mark: «nos» (indirect object pronoun or direct object pronoun), unless it comes after a preposition: «Nós gostamos muito de bolo. Eles deram-nos então um bolo de chocolate. Infelizmente para nós, o bolo era-nos enjoativo.» = "We like cake a lot. They then gave us a chocolate cake. Unfortunately for us, the cake was disagreeably sweet for us." Notice that, the fourth example uses «nos» in the Portuguese sentence because it is an indirect object pronoun, even though in English it comes after a preposition. Only if it comes after a preposition in the Portuguese sentence should it be written as «nós». If I rewrote that part of the sentence with a preposition, it would read «... o bolo era enjoativo para nós.».
Thank you for your response. I should've been clearer, though. I was actually wanting to know about the verbs. I have been noticing that the conjugation feature always gives two options for the nòs form. For example, apresentámos or apresentamos. I'm wondering if the accent is just a matter of preference, a difference between Brazilian Portuguese and European Portuguese or conditional?