<font color="blue"> Personally, I am awful about small engine maintenance. I always think I will use it "one more time" in the fall, then forget about it and in the spring, the gas has been sitting in it all winter .... when I grab a Stihl, I am in for a frustrating 10 minutes of cranking, fiddling with the choke, feathering the throttle, cussing and promising myself that I will no longer listen to the sales guys at my local farm store talk about the superiority of Stihl. </font>
I think that if you put some fresh fuel and a new plug in your Stihl it would run very nicely.
I don't judge the "superiority" of a piece of power equipment by how much neglect it can tolerate, but rather by how it functions when given adequate/minimal maintenance.
On topic: I'd recommend a Stihl MS260 Pro with a 16" bar and .325 chain. This is one of the finest chain saws ever built and should last a lifetime and perform beautifully. I highly recommend the Stihl Rollamatic ES bar (solid, not laminated), and when that wears out, an Oregon PowerMatch. Also seriously consider using non-safety chain; if you keep a firm grip on your saw and use it sensibly, kickback is not likely to harm you.
You're right on target with your list of safety equipment; logging helmet with face screen, chaps, gloves optional, and I'd add a pair of safety glasses for those little bits of flying wood and dust that happen to get past the screen. Chainsaw-resistant boots would be a nice touch, but good heavy boots should be OK.
Check out the thread "Felling a split tree" for general tips on tree felling. In general, a notch cut that is around 1/4 the diameter of the tree and a hinge that is about 1/10 the diameter of the tree are good guidelines. The felling cut is made level to the ground, not down at an angle, and should be made just slightly higher than the "v" of the notch cut. Get yourself three 10" or 12" plastic wedges for persuading trees with mildly unfavorable leans, and resist the temptation to leave too thick a hinge when pulling a tree over. Ten percent is all you need in a healthy tree; more than that, and you can easily barber-chair the tree (have it split up the middle, with the hinge not coming into play).
Watch for widow-makers (branches that might fall/break off during felling/fall on you and kill you), always have an exit route planned out for when the tree starts to go, avoid getting a tree hung up in another, and if you're not sure of what you're doing, don't do it.
Respect the wind, and don't cut through your hinges. Good tip about having a spare bar and chain with you; if you pinch your bar, detach your saw from it and put on the spare bar and chain. Then free the bar by mechanical means, such as pulling on the tree with a good bull rope attached to your drawbar. A 150', 9/16" Samson Stable-braid bull rope from Sherrill arborist supply will serve you very, very well; they're around $120 I think. A $10, 12-oz. throwbag, also from Sherrill, will help you throw it up into the tree. Learn to tie a running bowline for the end of the rope that attaches to the tree, and a bowline on a bight for attaching the rope to a shackle on your drawbar.
Once the bar is unstuck, continue the felling cut until you've got your 10% hinge, and pull her over.
On your hilly terrain, pay extra careful attention to how the tree is going to behave when it lands. They can roll, bounce and kick quite a bit, and can easily harm you, your tractor or your saw when they land on uneven ground.
If you have any doubts that your tractor is heavy enough/has enough traction to control the tree, don't use it. The bullrope is good for about 12,000 lbs. and your tractor will go flying. (No, I do not know this from personal experience). /forums/images/graemlins/smile.gif
Whatever you do, be careful. Trees are heavy and you can't fool physics. Take baby steps if you need to, build up your confidence, and then never get over-confident. Constantly respect and consider what can go wrong, and keep yourself out of trouble. Don't take chances. When you're about to take one, you'll know it. When that happens, stop, and make another plan.
Good luck,
John