Congratulations!

Don't worry too much about 5 days a week for a while. You'll need time to build up the strength and endurance. I've been riding for about 8 months now and am just now able to do all 5 days without feeling like my legs are on fire coming home on Friday. Even 3 days a week is enough to start noticing a real difference in your aerobic health.

Cars stink, but if you ride at the same time every day, they'll get used to you and give you some space (hopefully). Try not to break off any mirrors, but do speak to them if they've passed you too closely. A lot of times, at least in my experience, they don't realize how close they were and will apologize.

You'll also want some hi-viz clothing if you don't have it already. Once I started wearing a yellow construction vest from Home Depot, cars gave me noticeably more room, especially in the morning. And they're big enough to wear over a sweatshirt or jacket on those cold days.