Well since it seems you are looking for advice on certain breeds based on personal experiences, I am here to offer my personal experience on the Shiba, and based on your description, I would recommend one, amongst many other breeds too..but since I have personal experience with the Shiba here goes..
- Shiba was my first dog as a young adult, living in a very small apartment, and he was quite content, and extremely low maintenance (perfect for a first timer, IMO)
- He was satisfied with three, 10-20 minute walks a day. I worked 10 - 12 hours a day, so sometimes this was all I could offer.. but I did go for longer walks, jogs or take him to the dog park a few times a week when I could
- Shibas aren't known barkers.. they rarely bark, unless there's a good reason or they sense a potential threat. This was a VERY good thing living in an apartment.. my nieghbors always commented how they could NEVER tell I had a dog in my apartment. (but they are excellent watchdogs, and very protective)
- They are very calm, relaxed, laid-back dogs for the most part, and are well known for their 'cat-like' traits. They are extremely clean, they clean themselves just like a cat, too, but they also are VERY good as far as not having accidents in the house. Because they are very clean dogs, they absolutely hate having dirty houses, which means they would rather put themselves through discomfort than soil in your house..its often said, and even the breeder I purchased mine from, in her years of experience with them, has said its very uncommon for a Shiba puppy over 5 months old to have accidents, and most are already fairly well potty trained by 6 weeks old.
- They are extremely bold, brilliant, intuitive dogs..very easy to train, and generally will do anything you want from them.. if you want a couch potato he will be a couch potato.. if you want to do go for a 10 mile hike he'll be down for that, if you want to travel and take him with you, they are usually very good travellers too!
But there are downsides.. Shiba's do shed, and while they don't require extensive grooming, brushing weekly and bathing every couple months is helpful. Investing in a good vacuum cleaner is also very helpful.
Also, in your situation one thing to consider is a dog with high prey drive..Shiba's are natural-born hunters and killers, I know you said rats will have no interaction with your new potential dog, but any dog with a natural hunting instinct may definitely try to catch them if they were ever loose for any reason. My Shiba has hunted and killed mice and squirrels, though he is not a working hunter, it's just instinct.
There are Shiba Rescue groups out there... so its possible to adopt one that suits your needs if you were to consider this breed. There are lots of wonderful dogs out there I know, but I'm just giving my personal experience with this breed. I did research for almost a year and narrowed it down to the Shiba for my first dog, and I never looked back.. he was absolutely perfect and suit my needs and wants in a dog to the T. If anything, he was great for a newbie because he was so undemanding, did so much for me yet expected nothing in return.. he was happy and content no matter what.
Anyways, just wanted to share. Good luck and hope you guys find the right dog!