So if you’re in Kisiment and you keep walking through Remera, you’ll eventually end up in Kimironko, home of the Kimironko Market and not much else (as far as I know). Fortunately the market is packed with things so you should be able to do your grocery shopping here. It can be a bit overwhelming at first so it might be a good idea to hire one of the local guys who hang out there to lead you around on your first trip.
As it is fairly far from town, it’s not the most popular place for expats to live, but with a car you’ll be fine. I’ve had friends living here complaining about finding motos in the evenings, but there are a few buses going into town. From what I’ve heard, there’s a few really nice houses here, and most of them are rented out for less than anything you would find closer to town.