PTOs do add more places for things to leak, but as mentioned, failure to check the trans fluid is what causes problems. You could actually see the pto as helping a bit as it adds sump capacity.
They do make electrically shifted ptos, and I have considered trying to use a vacuum or air cylinder. Vacuum would have to be pretty good sized, but I think it's doable. You don't need much force to engage the pto.
From what I've seen, PTO specing is fairly complicated. Among other things, it looks like different gear ratios in the trans matter, at least on the ZF5, so be aware of that.
Specing the hydraulic side is also somewhat complex - you'll want to figure out what flow rate/pressure you need for what you're planning to do and then pick a pump that will work at the speed you're going to have off the pto. Too much flow is a waste, and will require larger hoses/tubing as well as possibly causing issues due to backpressure. Too little is also bad for obvious reasons. Make sure you include a relief valve, and also consider that plumbing in multiple systems is not always as easy as you'd think, (ie running the winch & the dump bed, particularly if it's 2 different valves) and setting up for a add on remote like you mention is it's own can of worms. Not that it's impossible, or even that hard, it's just the you need to engineer the system to do what you want and make sure it'll all work together rather than just sticking a bunch of bit together.
