I would say start with putting fluid in the tires. Even the front tires will hold 16+ lbs each, for a minimum of 32 lbs extra on front of the tractor. It does help, I used a plow this year for the first time, and was light in the front. I put winsheild washer fluid in the tires (2 gals ea. tire) and it was enough.I think you're more likely to have trouble steering then to actually break something. When you first use an implement go slow with it and be aware of any changes in steering feel. If you have a rear blade on and lifted for instance and are driving up a hill that is where you can suddenly discover how light the front end is. Some front weight can be good insurance, although it will make the steering a bit heavier.
I don't know about capacity, but the capability is about 10% more than the MF1450 - 1855 tractors which are capable of lifting a 320 lb MF4850 tiller out of the ground.What is the lifting capacity of the 3pt hitch on an MF16?
As long as the legs are still on the engine hoist, not a problem. With no spreader legs, and working against the 3PH, big problem. Not 4X the weight on the front, but certainly 80% of the payload weight, or 500 lb, whichever is greater. More, if the reach is more than 4'.If you are going to lifting from a car with 4-5' extension, the leverage is going to lift the front of the tractor. An engineer can chime in, but I think you would need 4x the weight on the front of the tractor.