Etymology 1 (kaa)
kaa (ma class, plural makaa)
1) charcoal (substance)
Etymology 1 (-kaa)
From Bantu. Related to Zulu hlala.
-kaa (infinitive kukaa)
1) to stay, to live
(We can add "to sit down" to this. According to the conjugation chart, the imperative is "Kaa!", and this would be "Sit down!" and there is also a second form for imperatives taking an object, "% kae!")
From Wiktionary: https://en.wiktionary.org/wiki/kaa
I guess yes. I am only a learner here though.
However the day idea of associating 'to stand' and 'to stop' occurs as well in Arabic (waqafa /وقف) and Turkish (durmak). Turkish might be a bit unrelated but Arabic has strong influences into Suaheli.
The same idea occurs for associating 'to sit' with 'to live (in a place) Arabic (djalasa جلس), Turkish (oturmak)