To all of the above: yes.
Does that sound okay or is this a solo job? Or does it depend on the owner?
I work full time at my main job and my partner is a full time student, and we still host Rover dogs usually 1-2 weeks out of the month. I work three 12 hour shifts per week while my partner is in class M-F for a few hours each day. In any given week there are 1-2 days where we will both be gone for a few hours at a time. For us, unless it's a dog we know and who is comfortable with us, we just avoid taking a new dog on a day where we'll both be out of the house, because we want to give them plenty of time to settle in and get used to us, our home and our dogs before leaving. I do this by marking my work days off on the calendar, and I let our clients know what our schedules are like before booking so they know how much time we'll be spending with their dogs. Many of our clients have dogs who are often home during the day while they are at work, and they're fine with us being out of the house for a few hours.
Also, if my roommate is helping with the care should I put him on my profile too?
Yeah, that's a good idea. Generally clients should be aware of and have the chance to meet anyone who will be providing care. Some dogs may be reactive to different types of people; many dogs are afraid of men, or men with beards, or people with hats/hoods, so having everyone who will be caring for the dog present for the meet and greet whenever possible can help prepare you for any weird scenarios that may occur during the stay. That said, coordinating everyone's schedules for a M&G can be difficult, so at the very least make sure he's credited in your profile and make your clients aware of the role he will play, and ask clients if their dog has a problem with any particular kind of person.
Your situation may not make you the best match for some dogs, but I assure you there are plenty of people out there who will be happy with your arrangement.
You can do that BUT you should leave the dog in your house unattended if they have anxiety, if they don't they might need medicine at a specific time and if they're normal kind of dogs they always bark if you're not home. So maybe schedule the dog sitting days when you have a day(s) off .