As far as the OP's questions go I'd say leave Evil Eye be and go with Slumber and/or Misfortune. You'll have much more influence on combat. I've just reached level 5 as a witch in PFS and here's what I've learnt:
1) Lead with Slumber unless you know/believe the targets are immune/resistant. That's when you turn to Misfortune. Even one round of slumber is better than cackling your way through multiple misfortune rounds.
2) Misfortune is next best, particularly if you have other casters in your party with Save or Suffer spells.
3) Evil Eye is more of a fall back if I'm up against sleep immune and/or high WIS enemies. It just edges out Good Fortune mostly because your allies can only benefit from GF 1/day.
4) Cackle, Cackle, Cackle. All turns where you've misfortuned must have a cackle.
5) GM's will come for you and given the 30ft range of Hex you will be hit and ganged up on often if your party doesn't protect you. Spacing is important. Your party needs to ensure you have 5ft step options to get out of harms way and for them to fill the gap to protect you.
* A lot of the Witch's spells double up on what you already do so make sure you're not over committing to compulsions, Will saves, etc.
6) Gear wise I think AC and Con bumps are the way to go given you're a GM's first target. Other tricks to generate miss chances go along way.
7) Spells tend to be cast at range or out of combat as you're mostly just Hexing. In the long run I'm building towards Quicken Spell with the plan being to spend my turn doing Quicken Ill Omen, Hex (Sleep/Misfortune), Cackle and 5ft step if required.
8) Healing Hex has been pretty good to free up spell slots from healing and conserve curing wands.
9) I'd also suggest having the odd combat where you don't slumber or misfortune. Why? Mostly to give your GM a break as some will find the witch a frustrating character to have in the game and sometimes it's best to just let your party have their moment to shine. I mostly pick a combat where I feel the challenge is minor and will turn to the hexes if I feel it's things are starting to get out of hand against us through freaky dice rolls.