When I park mine it is under a shed so I just boom it down, what ever position the bucket is in is where it stays. IF I am parking it temporarily outside especially if on a slope, I tilt it to place the toothbar into the ground and put slight pressure on it to slightly raise the front of the tractor. This assures it doesnt run off on me. On some of my slope, if it is flat the tractor will still roll back.
I have never had a hydraulic cylinder rust on anything. We (and almost every other farmer around) didnt have sheds to store all the disks and stuff with cylinders on them back in the 60's and left them set all fall and winter till spring when we started again. I never saw any pitting or rust form on the chrome plating on the rods on any of our hydraulic cylinders. The cylinders we use today may or may not be as well plated. I never worry about them on my FEL now and they stay super shiny. Use your own discretion, oil or grease or leave them as is, I think you will have the same results. Folding them in would prevent accidently dropping something on them and chipping the chrome plating. I wouldnt keep my exposed cylinders anywhere close to welding or grinding operations either.