Get the 60 day visa and then extend if you plan to leave between day 60 and 90. When you return, you can return visa exempt for 30 days (plus another 30 days extension if needed).
I had looked at the multi entry visa last year, and I honestly do not see it's purpose for most tourists unless you already have set dates you plan to travel.
, depends. I have checked in for a flight over 3 hours before. The girls were at the counter, so I went up, and they checked me in. I had lounge access, so I could use that time to relax.
But you are right, usually they open 3 hours before, if they don't have flights before yours.
I would get there at 9am at the latest. If the specific airline has multiple flights leaving within 2 hours of each other, then it can get busy at check in. The line up can go from 3 people to 30 in 15 minutes.