Experience is given out equally, no splitting. If you're playing with two characters without lone wolf, you're just playing a gimped party.
The lone wolf talent gives an extra skill point per level, I'd argue it's pretty much mandatory if you want hybrid characters. And yes, you take it during character creation or not at all, that skill point bonus is not retroactive.
The game's difficulty ramps up around level 10, so I reckon your two man party is probably screwed.
Regarding schools of magic, I have two mages at level 18, both with lone wolf. I've mastered two schools of magic on each along with 3 or 4 points in several support skills (crafting, telekinesis, willpower, bodybuilding). I don't recommend trying to master more than two schools, but taking one or two points in other schools to diversify a bit is fine, there are plenty of good helpful low level spells.
