If you don't have a pet yet, you'll likely want to do a search once you have a specific animal in mind - age/breed/health history can all affect how much you'll pay for insurance. Things to watch out for: lifetime vs annual limits for conditions, age restrictions (a lot of companies won't insure "senior" pets, you'll need to check with them as to their definition of senior).
Re: dogs and working, it's down to the dog. We've got a big dog (labrador/shepherd/greyhound mix) who is hardly the poster child for living in a city (we lived in London for 3 years) or being left alone for long periods (with commuting, my husband and I are gone about 12 hours/day). He does fine - he sleeps during the day, the neighbours say he never barks, and he gets walked right before we leave and right after we get home. You can also look into a dog walking service so that your dog could get out during the day for exercise/bathroom breaks.