I've done a good bit of editing work and have read many a manual. In general, your diesel engine should be warmed for at least 5 minutes before you begin operating it. Also, if cold, don't operate the hydraulics until the fluid has had time to warm up. It can damage the pump if you operate the cold, thicker fluid.
I don't agree that a non-tubro diesel doen't require a cool down. A turbo just requires a LONGER cool down. Your engine will have a longer, better life if you idle it at least for a minute or two, and a good bit longer for turbos.
I can't resist addressing the Lean toward the side that lifts comment. If you're on a lawnmower, that might work, but on the average tractor, your weight is not going to be much noticed. Good advice on dropping the FEL / 3pt implement in a hurry. A rollover usually happens much faster than most folks would believe. You only have a few seconds to react.
The thing about keeping the loader low is because carrying high can help with momentum in a rollover, and it would also take longer to get it to the ground. One can roll over on what appears to be flat ground. One example: Loader filled, riding high, one wheel slips into a depression/hole in the ground, over goes the tractor in a blink.
One major safety issue. Roll Over Protection Systems (ROPS). If you have one, use it. When using it, keep your seatbelt on. If you don't have a ROPS, then don't use a seatbelt. In a rollover, with seatbelt and ROPS, you will be held in the "safety zone" of the ROPS. If you don't have your seatbelt on, the ROPS can crush you. If you don't have ROPS and wear a seatbelt, in a rollover, the tractor will crush you as you cannot attempt to jump away.
There is much more that you need to know. One good way would be to try to find some owner's manuals for tractors. They don't have to be for the one you own. Read the safety tips in those. Even a public library may have some you can read.
John