Oh hey Past Dean, I’m going to answer your questions for you!
Q1 Is there a new version of either hardware or firmware due soon?
A1 The SmartThings v2 hub came out on 03-Sep-2015, 4 months after you posted.
Q2 I leave my car in the garage and take transit to work, should I consider dropping a Presence Sensor in the car to confirm it is located at home?
A2 It sort of works, but the distance from the hub and the metal body of the car made it a little difficult - so you gave it to your room mate to use instead.
Q3 If any adult users of the home have the app installed, will they need a Presence Sensor?
A3 They don’t need a Presence Sensor if they have the phone app.
Q4 Any ideas what other clever uses someone could put to a Presence Sensor?
A4 As many have pointed out, you can hide it and trigger things on it appearing.
Q5 Do these kind of thermostats control heat and air conditioning, or would I need a separate control for the AC as well as the heating?
A5 Most of them - including the ecobee3 you got - control heat, air conditioning, and humidifiers. Certain of them can even do UV lamps and dehumidifiers.
Q6 Are there other thermostats I should consider, such as the Lyric?
A6 The ecobee3 is excellent, you’re awesome for picking one. Go you.
Q7 Will these sensors report the status of the door to the hub, obviating the need for an open/close sensor?
A7 Nope, they tell you if the door is locked or not - which, if it happens when the door is open, is less than optimal.
Q8 Is there a cheaper alternative for the garage access door?
A8 No, the GD00Z-4 is UL certified and makes all sorts of fun beeps and flashes.
Q9 Is there a cheaper alternative for the basement suite door?
A9 Yes, there are different smartlock types available.
Q10 Will a Open/Closed Sensor work just as well?
A10 It will, but that temperature tracking is actually quite useful. Plus, you live in Canada and getting ANYTHING delivered here costs extra.
Q11 Would the Multi Sensor allow me to confirm the temperature in the garage for use in a scene?
A11 It will - and you’ve been logging temperatures to Google Sheets for quite some time.
Q12 Will adding this extend the mesh to the garage, approximately 5 meters from the house?
A12 It did indeed do so, and has made the sensors in the garage a little more reliable.
Q13 Any other danger and damage sensors I should consider?
A13 Maybe the sensors for the windows, when you replace them. Maybe some more leak sensors. Apart from that, just wait and see what is released.
Q14 What interesting uses have these been put to?
A14 The humidity sensors? Not much. Leak sensors are better. Plus, your ecobee3 tells you the humidity of your living room.
Q15 I’m assuming most people are using these to tell if something has been moved or actuated, but has anyone come up with any creative uses?
A15 The Cube That Does Stuff is one. There are others - such as a post has arrived idea, but this won’t work with your metal mailbox.
Q16 We’re going to get a cat - how can we stop the beast turning on all the lights? By knowing that we’re all away? Does this mean that if I am home, the cat can turn on all the lights by running around?
A16 You haven’t got a cat yet, but your downstairs neighbour does, and it turns on the lights in the utility room and the storage room. But, they turn off after 5 minutes of inactivity anyway, and they’re LED, and this rule is only active between Sunset-2H and Sunrise+2H (it’s dark in the basement).
Q17 How long is the battery life for most of the SmartSense products?
A17 This one is odd - the presence sensor polls way too much, and the batter is almost dead. The others are about half power. I’d expect to be replacing the batteries after a year or two, at this rate.
Q18 Would it be possible to write a text-based log of events to OneNote, EverNote, or another destination using IFTTT? Has anyone done this?
A18 Thanks to the Google Sheets logging, and previously IFTTT, you have a lot of data collected.
Now work out some more questions for the next year!