1) You can prepare and cast what the table of spells per day says you can, plus any given for your school, plus any given for high intelligence.
For an example, a 1st level Universalist Wizard with 18 Int has 2 first level slots, while a 1st level Conjuration Specialist Wizard with 18 Int has 3, one of which that can only be used to prepare a Conjuration spell.
2) You can prepare what the table of spells per day says you can, but you can cast them as many times per day as you want. Neither high Int nor selecting a specialist school will increase this number.
3) It gives you an extra slot of that level to prepare whatever you want.
4) It's in the CRB. Page 79, in the Wizard section:
Quote:
Each arcane school gives the wizard a number of school powers. In addition, specialist wizards receive an additional spell slot of each spell level he can cast, from 1st on up. Each day, a wizard can prepare a spell from his specialty school in that slot. This spell must be in the
wizard’s spellbook. A wizard can select a spell modified by a metamagic feat to prepare in his school slot, but it uses up a higher-level spell slot. Wizards with the universalist school do not receive a school slot.
