Learn Italian: Sai dove abita Anna? - Do you know where Anna lives?

Sai is the informal "you" (singular) form of the verb sapere (to know). Sapere is highly irregular, so it does not follow the standard rules for dropping the -ere and adding normal verb endings. You simply have to memorize forms like sai.

I learned that the verb for "to know" is conoscere. Why are we using sapere here?

Italian has two different verbs for "to know". We use sapere when talking about knowing a fact or a piece of information, such as where someone lives. Conoscere is used when you are acquainted with a person, place, or thing. If you wanted to ask "Do you know Anna?", you would use conosci Anna? instead.

Why is the word order dove abita Anna (where lives Anna) instead of dove Anna abita?

In Italian questions, it is very common and natural to put the subject (Anna) after the verb (abita), especially right after a question word like dove (where). While English strictly requires "where Anna lives," Italian prefers the flexible word order of dove abita Anna.

Can I use the verb vivere (to live) in this sentence instead of abitare?