If you buy a high end wheel, you might do better online. For a first wheel the advice of a bike store might be better. I'm pretty sure most 700c front wheels are the same width, but if not hopefully someone will correct me on that before you buy the wrong wheel. Yes you're going to need a tire (and a tube) in addition to the wheel. You could probably find the specs for your bike online and buy the same front wheel that comes with your bike originally if that makes you feel more comfortable.
Sorry you had your wheel get stolen. Just so you know (and hopefully don't take it personally) there are a lot of lbs supporters/employees/owners on here so don't be surprised if they attack someone without much knowledge/experience in this area for buying online. People who know what they want and drop $3k on wheels (yes that's each) online don't get as much grief. So, while if you have questions, it might be more reassuring to have people who can actually see the bike help you in a bike shop, don't let them make you feel like you're the bad guy in this whole theft thing because you chose to buy a replacement online.