Regarding the Channelling Skill
When ever I envision a group of mages or spell users of some sort getting together and mainly focusing on a ritual, they connect to each other, feeding their power into the Principle. When I have cult activity they are all using Channelling. Most of my players never think of it, although at one time we had 3 mages in the party and we developed Channelling and used it to over charge spells. Users of channelling should only share with their own ilk.
Priests and Mentalists still have to develop PP, so that means it can be taken away. Since Flow storms or micro storms or even a surge of unexpected power or influence are of the Arcane flavour so PP can be taken away or given.
To explain further: In my games I conclude that the Spell caster, no matter what Realm, is doing their best to maximize their PP development. So at any one time they are "topped up". For storing ambient PPs I give them their PP total + 50%. I have played in games where the GM let us store to our hearts content. It was ridiculous. I stored so much power that I took me 4 game sessions to start using my own PP and I had a x3 multiplier. Fun but Ridiculous!
Basically anything derived by the Flows is subject to the flows. Psychics are not derived nor are they a derivative of the Flows.
Although My mages can feel the flows from some distance, I don't give them any real benefit till they are within 2 km of them. At about the 2k mark they are getting one extra PP a round that they can tap but not store. Every half km gives them an extra PP. At one Km (from the flow) they can start to store up to half their normal PP (no multipliers). As they leave vicinity, farther then 2k, the stored PP will bleed of at 1 PP an hour. Unless they have the right profession, or spells most mages have no real way of storing extra PP. Essence users would store the PP in their Aura, while the Mentalist charges their Body.
The above may change with the power of the Flow or Node. It is not perfect but I do a fair bit on the fly. I never give more then 6 free PP a round and even then it has to be a major node.
I am probably arguing semantics here but I think Spells would not get cheaper the closer to the Node/flow you are. Spells always cost the same to power them. By lowering the casting cost it sort of implies that the Players are plucking the Spell out of the air and casting from there. That could also imply that some spells work better near certain flows... which I think was stated earlier. If An elementalist was casting spells then yea, distance from fire or ice or water would make a huge difference. Casting a 10 point spell will aways cost 10 points, but being in vicinity of a Flow or Node will make it easer to pay the price as the spell caster can draw upon the ambient PP in the area. I also seem to remember something stating that sometimes it is much harder to cast while near a node or flow as the power is being pulled from you. A fast moving Flow would act like a river and draw you under, draining your PP.
Just the ramblings of my fractured imagination.