Barry,
The smaller 1026R should do everything you need to do including running a small 3PH
chipper. I say that because the x700 series will do it, recognize once you clean up the place there won't be much left to do but mowing and snow clearing. In your shoes I would go with the 1026R and auto connect deck. If you are mowing you would remove the loader, so disconnecting the lines is a non issue.
About the implements, you can buy most of the stuff on your list for the difference in price between a 1026R and a 2520. Don't see the need for the brushhog for an acre that you are clearing and cleaning up, The auto connect deck will do all the mowing you need to do. Something not mentioned is the fact that you could buy a couple of pto drive lines for your Dad's pto equipment and swap them out easily when using a different tractor. That would be alot more cost effective solution.
With my x749 I do more utility work than mowing so far and have several implements to use with the 3PH. Thhis includes a DR
chipper, 5' landscape rake, 4' boxblade, 5' rear blade, 4' landplane grader, 6' pine needle rake, Howard HR4 5' tiller and a one row cultivator. I also have various pull type implements, MC519 collection cart, spin spreaders, drop spreaders, steel carts and a lawn roller. Just saying if a x700 series will work for all of these attachments then a 1026R with the extras such as a fel, mmm and backhoe that are all quick connect should work out great for you. The auto connect features are key here, this and an IMatch makes changing implements out fun by comparison.
The 2520 is a great little tractor too and would be better if you need the extra ground clearance. My only issue with the 2520 is once you clean up the acre you have then all you really need is a riding mower and that sounds like the 1026R will be more than you need.