6. As mentioned by others, the location is a bit off. There seem to be many offices in the area so if you have business nearby it would be great, but not as good for tourists. The Canopy location is much better, but I walked past the construction site and it didn't look anywhere near to being ready to open in the next 3 months.
As mentioned, tram 2 does take you to the main bus station and the main train station. You can buy 30-minute tickets from the newsagent kiosks for 4kn each (15kn from the driver). Paper ticket validators are only at the very front and sometimes the very back of the tram. There are smartcard validators throughout the tram, but I didn't investigate this further as you probably won't take the tram that often unless you are repeatedly travelling far.
I had several issues with the trams: when a ticket is only 4kn then the hotel is just a bit too far to walk, yet I ended up walking half the time.
This summer's European heatwave still seems to be ongoing in Croatia, and Google maps reporting of Zagreb tram times is inaccurate. The first trip to the hotel, I couldn't even push through the hot and smelly crowd to reach the validator so it was a free trip. The second time, I missed the tram by 30 seconds because Google said it was coming in 2 minutes. There is no shelter so I just walked rather than waiting under scorching sun for another 12 minutes (you can walk under shade of buildings).
The third time, I took a different tram because number 2 was not coming for 15 minutes, but the driver was told to finish short and turn back, so got turfed out and it was faster to just walk back as my ticket would have expired by the time the next tram + one transfer arrived at the hotel.
8. The hotel's airport transfer is now 140kn while the bus from the bus station remains 30kn. Worth considering if you have 4 people, or 3 with luggage, or hate public transport.
I live in Zagreb, and I would prefer location of DT vs Canopy, because Zagreb is safe city, and trams are driving until midnight (last tour of trams goes at 11pm from the first stop in all directions). Night tram/bus service exists, but it is not convenient because there is only 1 in 60/90 minutes. Yes, Canopy is closer to main square or Zrinjevac, but I would say that DT is also within walking distance (or you can take half hour drive with a tram), especially off rush hours (I would say that rush hours in Zagreb are 7:30-9:00 and 16:00-18:00). Canopy is more convenient for railway station, but if you are going to/from bus station (even for the airport) I would prefer to go to DT, and I would not wait for a tram number 2, rather take a 10 minute walk (if you do not have some bulky luggage).
To be honest, we do not rely on tram schedule, because at least half of the tram rails are on the car road so it is very hard for them to predict exact timing down the route (they obey timing hard only on first station, but a tram does not wait for scheduled departure on other stations). They try to make it as correct as possible, but some discrepancies occur often (especially after 10 pm trams often arrive earlier than planned). Our way is to go to astation look at the arrivals board (if exists) and decide whether to take the first tram in desired direction (I know that tourists prefer follow suggested routing, but tram network is not complicated, a lot of lines overlap so you can easily route yourself by alternative tram if you know where are you heading).
Regarding taxis to the airport, Uber is alternative, it starts (without surge) with 110kn and if it is off peak hour you can make it with that amount...