Is it usually the sentence structure, that "tu" comes before the verb? (I'm asking because I would have said "Mój tata jest tutaj")
Where would the negative go in, "My dad is not here."? Would it be "Mój tata tu nie jest."?
It's not exactly wrong, but it sounds strange to me. Generally, for 'not being somewhere' Polish uses a completely different construction. "Mojego taty tu nie ma"/"Nie ma tu mojego taty". So "my dad" takes Genitive, and there rest of the sentence would be literally translated as "There has not... here". Which sounds absurd from the point of view of English, but that's how it works in Polish.