Actually i think maelstrom is perfectly fine (even this iteration). Throwsin (like all ranged chars) is great for leveling, but she gets weak (squishy as fuck) at end of terror and she's quite vulnerable in destruction (as all sins would be).
smax all 3 ways and perfect being, and then the rest of the skills are up to you.
During lvling i would smax storm crows and maelstrom and use those 2 for clearing most stuff. TU balanced knife is a perfect weapon until end of terror. Armor: TU splint or chain mail. Most veterans say split mail is superior (3 elements of dmg + DR%), but chain mail has proc on striking. Up to you.
Rest of armor is flexible, i think i used TU tiara for elemental dmg, but you could do whatever you feel works.
By end game, i used trackers set, so i allocated enough points into storm crows for the synergy with scorpion blade proc (from set). Then rest into maelstrom i believe.
Wychwind is generally kept at 1 point because there's so many skills you could invest into by end game. And even at 1 point WW is arguably the best skill in the entire game. Beyond perfect being and 3 ways (and yes that is the uberskill i would pick), you have vampiric icon, blink (for lower spell timer), etc.
You should try out various combinations of skills to get a feeling for what works best with you. Sins are more about personal skill and game play than items because of how squishy they are.