Yes, kukaa means to sit, to stay, to live (in), etc. If you feel that an answer should be accepted, you can use the report function and the course team will review it.
Thanks, kshuck2! I didn't want to use the report function until I heard from people more fluent in Swahili; I'm just beginning the course.
For "please have a seat"/sitting down - I have only heard -kaa so far. Or maybe this is regional?
You're right! It is a very common informal way to say "have a seat", but it literally just means "stay". I love these idiomatic expressions that are used instead of literal statements. My favorite is when you want someone to stop running, driving, walking, etc. Sometimes instead of the literal "stop", you'd say "simama!"/"stand!" instead, at least in Kenya.