First, take a look at this:
http://community.wizards.com/go/thread/view/75882/19870778/The_Dervish_HandbookBe aware that Dervish isn't too good a class. It's not bad either, but usually you can do similar things with far less sacrifice. Barbarian 1 for Lion Totem, Cloistered Cleric 1 for Travel Devotion and a bunch of turning attempts or Binder 3 for Paimon's Dance of Death usually trumps over Dervish Dance. That said, you can take those in addition to Dervish, as they sinergyze nicely with the class (Whirling frenzy, knowledge devotion for free, Dex to dmg...).
Anyway, if you still want to use Dervish, I'd go all the way until the end, because you -need- those dances to be effective, and there is no way to get them aside of levels in Dervish. And the capstone is pretty decent.
Feats. You already have the requirements, so grab Elusive Target (Complete Warrior) ASAP. It's a great feat for everyone, even more for someone provoking lots of OAs. Also, grab Acrobatic Strike (PHII), as it is a +4 to attack by the face.
Also, seeing as you'll have the posibility to PA for a decent amount, think on getting Shock trooper and any PA enhancing feats.
The guide I gave before suggested getting Close Quarters Combat. I fully agree. Grappling on any non strength focused character is lethal.
You've said you can't use ToB, but maybe you can get the feats if you compromise not to use maneuvers. If that's the case, try to get shadow blade + Razor Gloom (if you are allowed to use stances) or Stormguard Trooper (if you aren't).