I think we need to back up a bit. When you say *down at the farm", do you mean the trees are "down" at the farm or "down at the farm". If indeed they are still standing at the farm and are 4 feet across and of the sprawling nature, have them cut down. Big trees can make you dead quite fast. There are techniques I know to get trees cut more than twice the bar length that involve fan,plunge and notch cuts, but I'd need to show you rather than talk you through it as you can do this job with a 20 " bar but we never cut a sprawling 4' tree down without limbing it first because even down without limbing, these trees can create your end of days right quick. Plus, we had all the equipment.
I do not know the answer to your second part as I have seen Husky saws that say "Sweden" on them but the box says "made in America". Who knows but the saw is a cut down version of the 575 which was not too well received when it first came out. The 570
is a cut down version of the 575 as xyz states. Saw is heavy for the power it makes but it will cut up those trees. Here's a proposition. If you have the trees professionally cut down, I'll inform you of techniques to cut up the tree with your current Sthil with 18" bar. Even this will be dangerous so it might be good to have only the fat parts cut up by the pro's or work up something with local haulers to sell the stems to a lumber mill.