Given your self imposed deadline you may already have bought, but here are some comments. 28 mm tires will work on smooth dirt or clay paths but they aren't ideal if you hit soft sand or a rock. Cyclocross racers use 30-33 mm tires, I believe. If you bought the Sirrus you can probably swap whatever tires you got for slightly fatter ones but ask the bike store what width of tire your bike wheel rims can accommodate.

Since you're going a fair distance you don't want a bike where you sit too upright as the poor aerodynamics will make you work too hard, and I would avoid suspension (slows you down a bit).

Drop bars are fine. The top level functions a lot like a flat bar and you can use the lower level when you want to get really low and aerodynamic.

You may not get the perfect bike the first time.

Did you really mean an 18m climb, or 180m? 18 m is not much to worry about and you can always get off and walk if it is too steep at first. 180m seems more likely and might take a few weeks to get really comfortable with.

Allow well over an hour (maybe 75 minutes) for your commute at first, but you will whittle it down to probably under an hour in due course.

Don't buy until you have done a test ride with the correct seat height.

I would definitely not buy a fixed gear bike, like the Norco Heart, as a newbie commuter with a mixed surface, hilly path. That is a choice for later, once you are really back into biking.