Tipping can always cause debates so it's a rather nice idea to ask here not there. Some position in WDW can't accept tips some can. Not that I know exactly but will reply based on my experience.
Steam Train Tour - DH is doing the Steam Train Tour in MK. The cost is ~$60
No tip nessecary here, I would guess that occasionally tips are offered.
Hairdresser - DD is going to a regular salon in the Yacht Club for an updo rather than BBB (she's "over" BBB

) The salon said ~$50.
Since this is out of the parks, it would be customary to tip for a hair appointment in the US, for both men or women. I'd go about %10.
BBB - DNeice is going to get dolled up at BBB. ~$55 for her package.
No tip nessecary here.
Private Pontoon to see Illuminations. The cost of the pontoon carrying 9 people is ~$350 - we're sharing it with colleagues of DH who will be there at the same time. We need to tip the captain, I have no idea how much. It's about 45 minutes duration I believe.
This is tough, when renting boats myself I've always tipped the dock hands $5. But since this isn't a rental it's a different question.
I've captained people on tours and recieved a tip about 1/2 the trips. Usually a couple bucks by about 2 out of 10 people on the boat. Of course it wasn't in WDW it was in the mountains, about 45+ minutes in duration. Trying to think of the price, it was a while ago so about $20 or $25 a person. So working out the math I received a tip of .5% because it was random.
You might try $2-$5 a person.
The main problem that causes a lot of argument is how tips are handled at WDW. What you encounter in the US that you will in WDW that are normally tipped are waiters/waitresses, valets, concierges, and bell hops. So I would follow customs and tip them.
Hairdressers too as noted above but why in the Yatch Club and not in BBB?
Because of Disney Policy. Some people are allowed to take tips like waiters others have to refuse it three times and if aren't allowed, hand it over to their manager. I was told by some CMs when there group gets enough tips they get a pizza party for lunch to use the tips.
Last time I tipped a concierge at WDW I was told no, no, no, then if I would like it donated to a specific charity. I said no, it was for you and thank you for the help. So maybe he kept it or it went to the pizza party pot.
I really enjoyed a doorman at my resort once. Saw him often, talked to him a bit, service was good towards me, incredible to DS. So I forced him to take $2, shoved it in his hand and denied it when he tried to give it back. I will never forget Laurent, the best door man ever.
Once of the greatest bits of contention is tipping your hotel maid. Some people believe really strong for this. There are studies that in the US this is not common, even at delux resorts and hotel chains. So just beause so many people on the DIS tip at the Wilderness lodge doesn't mean it's the correct or normal thing. Even at a 4seasons it's not customary.