The spells available are those to be found in the Ultimate Grimoire, and for starting characters will be assigned more or less randomly to reflect what was in the spellbook you stole from your trusting and benevolent master when you betrayed his trust and ran off to become an adventurer.
See your friendly neighbourhood GM for details.
Magic is handled very simply in this campaign.
All spells (or analogous magical powers) are bought individually. Power Pools (such as Multipowers) are not used for magic generally, although some individual spells with variable effects may be themselves built as Multipowers.
The Real Cost of each spell (i.e. the cost in character points after all Advantages and Limitations are applied) is divided by 3; this is the cost to the character of being able to cast the spell.
Example:
Hungas the Shaman wants a Fireball spell. He builds it as a 6d6 Energy Blast (30 Active Points) which costs him 10 points — 30 ÷ 3 = 10.
Not wanting to have to spend a whole ten precious points, he decides to give the spell the Gestures, Incantations, and Obvious Accessible Focus limitations (-1½), bringing the Real Cost down to 12, divided by 3 is only 4 character points. That's a bit cheaper, but not cheap enough for Hungas the Cheapskate.
He gives the spell 6 charges for an additional -¾, and because all magic must cost END (see below), adds the Costs END limitation for another -½. That brings the Real Cost down to 8, divided by 3 is 3 character points. That's about as cheap as he can get it without making it worthless as a combat spell, so that's it.
Magic skill rolls will be based on your personal MANA characteristic (at the standard -1 per 10 active pts in the power). Note that this will mean that as your mana is depleted, it will become more difficult to successfully cast spells. (I'll make a little chart so that we can see at a glance what your mana roll is, rather than have to do mental arithmetic all the time which HURT my BRANE).
Though not compulsory, almost all spells will have one or more of the Limitations Extra Time, Gestures, Incantations, and Focus (expendable or otherwise). Spells which mimic psychic powers tend to require Concentration. All spells, without exception, must cost Endurance (see below).