If it's a hydraulic shuttle like mine are, there is a modulating valve on the clutch pack that controls fluid flow that modulates lock up. I think it's externally adjustable but I've never fooled with either of mine.
Because it's load sensing, lock up can be abrupt at times. With mine I prefer abrupt because the faster the pack locks, the less slippage there is. I tend to throttle back when shuttling anyway. direction changes at any speed is hard on the damper plate.
The above only applies to a hydraulic shuttle, not the mechanical shuttle.
Far as fluid in the loader cylinders, they hold so little it's not of consequence. Like Wlofman said, loader on the ground with the bucket level.
My 9 holds 56 quarts and I think the 105 is about the same. The 14 gallon level won't change much with the cylinders full or empty, not that you can empty them anyway as they are double acting so you'll have fluid on one side of the piston or the other.
Be sure the tractor is level as that impacts fluid level a lot.
