If you want to grade your lane--don't go with the Bobcat. Nothing beats a 3 pt blade or box scraper for that. I couldn't even imagine trying to do that easily with a Bobcat On the other hand, a small tow behind (NOT 3 pt) box scraper is awesome for the job. I'd seriously consider one over a 3pt blade... for a very simple reason. Any 3 pt equipment, tends to dig or raise based on the fore/aft rock of the tractor...this actually results in a "wavy" surface (picture your tractor going over humps and what the 3 pt blade hung off the end will do.) Skid steer, same thing. A towed box scraper on the other hand, rides between two axles, and tends to "level out" the high spots and fill in the low spots. You can buy them with side to side tilt, or even a blade style with angling blade (think road grader!) I use my box scraper and loader all the time, almost never use the 3 pt blade.
Both JD and Kubota have very good small tractors. Kubota definitely wins on the rep, but JD service/parts is unmatched. You may also wish to look at the smaller New Holland tractors, they used to have a pretty nice machine. Just don't plan on using it like a bulldozer and you should be fine. Occasional use is the ticket on these machines.
Agree on the backhoe--no need. It will just sit in the shed. I have a large 3pt backhoe for a 100+ hp tractor that I haven't got out in 10+ years. If I want that kind of work done--I call the excavator guy.
As far as the PTO on the mower--its mostly common sense. Don't start or stop the mower at full throttle is a big one. Don't try to ram it through heavy wet grass or 3" brush. Slow down. Mow high--don't try to scalp the ground, and be constantly ramming the blades into the dirt. Keep the blades sharp. Pay attention to the instructions about adjustment on the slip clutch of the mower. (This is a big one, since they outlawed the use of asbestos, the clutch disks now "weld" to the plates. I have to take the clutch completely apart on my 8' Bushhog every year and loosen up the plates (they warned me, I didn't listen, I twisted a driveshaft... ) You want a mower wide enough to cover the tires of the tractor. I suggest you get a tractor big enough to handle that big of mower. I know that sounds like circular reasoning, but its really not...If the smallest tractor you are looking at needs a 5' mower to cover the wheels, make sure the tractor has the HP to handle that size of mower.