Howard,
I believe the 4010 and the 4110 are configured the same so I will answer your question based on my personal experience.
1. Installing/Removing the deck is a 10 minute job max. Like anything else, there's a learning curve, but JD has really done a good job in this category.
2. You need the latch kit to keep the mower up so you can use the 3 pt for other implements. I've heard cost range of between $75 and $90.
3. I have the 54 inch. The 60 inch is heavier and has wheels that rotate when you are turning. My brother runs two JD 425's. One has the 54 and the other the 60. He prefers the 60. I cannot comment on which provides a better cut, but with the rotating wheels, the 60 (in theory) should have a much lower chance of ripping up grass.
FWIW I am very happy with the 54, but you are mowing about an acre more than me. Sounds like the 60 may be a good fit.
Good Luck
Bob