As for "going gandalf" that point is silly. A: Ignoring city building to go learn flare is mind-numbingly stupid, B: Using your channeler in battle is risky and unnecessary, and C: You have heros to learn stuff in the field, your channeler should be safe at home.
A: That's why I said you should have conventional research. Because giving up city-building to learn Flare is mind-numbingly stupid, and if that was the only way to learn spells, it would make the game a nightmare.
B: Unless (s)he's so filled with essance that (s)he's super-powerful..... that's what going Gandalf means: you invest in your channeler and heroes instead of an army or empire.
C: And heroes take essance. See above.
I too was under the impression you explicitly meant 'finding spells in the field will favor channelers going out to combat without building cities.' I did not see an argument against this in what you said... Maybe it is just me, but I had the impression you meant that going out with your channeler might actualy be a good idea.
In the end it would be nice if we get spells and such through exploring, plundering and such. I am looking forward to getting more info on this infinite researching and such, since I am dreading it will be like GalCiv2 where there were so many techs that essentially did the exact same thing. (Oh look, another tech that improves photon cannons, making them onky slightly better and even if you equip your ships with them, the freed up room is not useful to do anything with it. Yay! Improvement!)
I would like to see a system somewhat equal to SMAC or MoM where you could slowly advance without the focus of the game being technological advantage like it is in Civ IV. Maybe a system where you can either steal ideas from neighbouring countries or get ideas from the local population would work. That way let us say that at the start of the game you have an idea or two. You can spend time into developing that idea. As your settlements grow and the population thrives, your inhabitants get some more free time because the standards of living improve. Some people get a good idea and spread it. You can then when you get to it develop that idea, and as such you gained an additonal research option. In the end then it will be needed to keep your population happy, because at random times your population might propose something you may research. The happier the locals and the higher the standard of living the higher the chance they will propose something.
This way you will depend on both what the locals propose - making what techs you have available different every time - and on how well you play - because the better you manage your population, the more often they will provide you with ideas for you to look into.