The total amount you will get towards your tier eligibility is the base fare only (shows up as the "Fare" line on your receipt"); fees and taxes on top of the base fare are not counted towards that total. You'll get credits a few days after you've flown each flight leg.

The only other means that I'm aware of to accrue status spend is via the RBC MasterCard (which - looking at the terms and conditions - is supposed to credit you $500 for each $15000 of spend up to $1500).

I've never been in a position where my status would drop, but I surmise that if you do not hit the $3000 in a given calendar year that you would drop back down to Teal.