1) I think any can do, the speacilisations are quite thematic imo. Personal favourite of mine is conjuration but it just depends how you want to play your wizard.
2) dumpiest to need: cha, str, wis, dex, con, int
Others might disagree.
3) cloak of resistance, scrolls, weapon to fall back on if absolutley needed.
4) improved initiative, spell focus are my faces
5) wizard is easier than it looks so dont worry ;)
You DID read Treantmonk's guide, then? Good. We have a place to start.
1. It's going to depend on what type of wizard you want to be. Divination is common (and probably the strongest) for the school power. Evocation is best for blaster's. Treantmonk does a good job of showing the control-centric style. There's a contrasting guide discussing blasting (the "Blockbuster Wizard") that you should read. Buffing wizards tend to either take divination for the power or transmutation if they're buffing themselves. For a starter wizard, I'd suggest a blaster. It's not the strongest type of wizard out there, but it's fun, and blasting spells are more straightforward. Plus, you still end up dabbling in other sorts of magic while focussing on blasting, and that's a nice way to slowly become accustomed to the other spells. As an evil wizard, you might be interested in trying your hand at necromancy. It's not what I'd pick because it's a more complicated and specialized route, but it's flavorful.
2. Int is all you really need. Dex and Con are both very helpful. Beyond that, you just need enough strength to carry your own things and enough wisdom to not ding your will save. Charisma can be completely dumped. There are few traits that allow you run diplomacy, bluff, and intimidate from Intelligence if you need face skills. There's one for UMD, too. As such, the dump order would be Cha, Str, Wis, Con, Dex, Int.
3. A collection of level 1 scrolls for utility. There's not a whole lot you'll need early on. I'd save for a cloak of resistance, the ioun stone that gives +1 to initiative, and an intelligence boosting headband. If you have a familiar, you can start a level 1 wand collection for level 5 or 7 when you take the improved familiar feat.
4. Depends entirely on what you want to do. Use the example build in the blockbuster guide if you go that route. Otherwise, let us know what direction you want to take your character and we'll go from there.
5. If you need help deciding on what you want your character to do, read Tark's guide to party tactics and examine what the other characters are preparing to cover. That should help you decide on what your own character can cover.
1. As Mystically Inclined says, Evocation is likely the easiest school for newbie wizards. However you should plan your build to pump up your damage or you'll be disappointed in seeing how fighters and barbarians deal 3x/4x your DPR.
If you're willing to spend some time in studying spells and think about strategies, you'd rather go on Conjuration (Teleport) or Transmutation (Enhancement).
As for opposition schools, I usually ban Enchantment (too many monsters are immune to mind-affecting, although some spells like Confusion are really nasty) and Necromancy, which has powerful spells but is a small school.
However, as you're planning an evil wizard you could opt to keep necromancy (hi, undedads!) and ban Abjuration instead, specially if you have a cleric in the party.
2. CHA and STR are the usual dump stats for wizards, pay attention to encumbrance (CHA may be useful against charmed creatures). Some also dump WIS (but failing Will saves really sucks).
INT is of course your main stat, then choose CON (HP & Fort. saves) or DEX (initiative, ranged touch & Ref saves) as 2nd and 3rd stat respectively.
3. Handy haversack if you dumped STR and your GM is strict on encumbrance. As said, some 1st level scroll. A +2 Headband of Vast Intelligence, to be upgraded whenever possible. A cloak of resistance. Some potions of cure wounds. Flasks of acid and alchemic fire.
4a. Skills: Spellcraft should be maxed out. Take some grade in Perception, and max it out via the headband. Then put grades in all knowledges, needed to identify enemy weaknesses. Fly will need some grade since 5th level, and you may find some extra language handy, especially if you are going summoning. Some sense motive, some UMD if you plan to have an Improved Familiar. Acrobatics might be useful as well to avoid AoO where a single step cannot get you out of troubles.
4b. If you plan to build a blaster (hint: Evocation/Admixture) you'll need a ton of metamagic and feats to power up your damage.
As an example (YMMV a lot) I'd go with
Traits: magical lineage (fireball), Lore Seeker (magic missile, fireball, choose another)
1. Spell Focus (Evocation), Spell Specialization: magic missile (you fire 2 missiles at 1st level, 3 at second)
3. Improved initiative or Toughness
5. Preferred spell: fireball, heighten spell (B)
6. Spell Specialization -> switch to fireball, now you cast at CL9.
7. Empower spell (now you cast a 15d6+3 fireball as a 4th level spell)
For other builds, you may want to take as a reference:
School: Conjuration/Teleport or Transmutation/Enhancement
Traits: Reactionary (+2 init), Focused Mind (+2 concentration) or Dangerously Curious (UMD as class ability).
1. Improved Initiative, Toughness
3. Combat Casting
5. Craft Wondrous Items (B), Spell focus: your favourite school
7. Improved Familiar (Faerie dragon rocks).
For a summon-centric build you may want to take Spell Focus at 3rd and Augment Summoning at 5, skipping combat casting.
5. As a general advice, you do not have to cast each round. Doing this, you'll end soon your spells per day.
Even if you go the blaster way, remember that anyone in the party can do damage, while there are things only the wizard can do. 90% of times, a Haste spell will deal more damage than any fireball.
Scribe scrolls! Even in ad adventuring day you can net out 2 hours of work, which allow you to write a 1st level scrolls @CL10 and 2nd level scrolls @CL5.
Depending on how good you are with tactics, a battlefield controller Conjurer is probably the best way to go. But you need to be aware of the best places to cast your Grease or Create Pit spell to get the maximum effectiveness in combat.
Blasting is a lot of fun, but at lower levels you will run out of juice fast. You do get Scribe Scroll for free, and if going the Evocation route I would suggest saving your money to scribe some scrolls so you have some extra ammo.
Looking at opposition schools, you will notice that Enchantment is pretty weak and makes a good choice. I personally would never give up Conjuration, Divination, or Abjuration. Illusion is really good also with some very important spells. Necromancy and Evocation are the only other schools I would consider dropping because of that. Typically I give up Necromancy and Enchantment.
Necromancy isn't the only form of magic with an evil flavor either. I can easily imagine a blaster wizard who enjoys watching his victims burn alive or otherwise suffer. There's also the enchanter who casually dominates passers-by to grow his small army of servants, slaves, and 'tools' (meat-shields). How about an illusionist that enjoys twisting people's fantasies into horribly scary nightmares so he can feed on their terror? Or the conjuration wizard with a fascination for demons or devils. Maybe he has a fiendish patron who has convinced him to view his time on the mortal plane as a 'pledge drive' for becoming a demon. Or the scholar who got a bit too far into research on shoggoths and eldritch horrors, and now isn't entirely in control of his own mind.