1. How does the Indiana Jones ride compare to Dinosaur at the Animal Kingdom in WDW? (I heard it's exactly the same track?)
I haven't been on Dinosaur since they changed the name from Countdown to Extinction! But from what I can remember, Dinosaur seemed more in your face w/ the animatronics while Indy isn't so much. I also remember Dinosaur being super loud, but that was probably bc I was really young. I think you'll like Indy anyways since the theme is different from Dinosaur.
2. How are crowds around the 23rd Oct to the 1st nov and do they do anything special for halloween?
The crowds are average during the weekends and the weekdays can be somewhat empty. And yes, DLR has Halloweentime! Main Street is decked out w/ Halloween decor (I'm not sure if they're having a Haunted Mansion Holiday this year) and DCA has their Candy Corn Acres in the Sunshine Plaza. There are lots of Halloween inspired treats in the bakeries and restaurants also. DCA also has a special event called Mickey's Trick or Treat Party where you have to buy extra tix for since the park is closed just for the event. It starts in the evenings and you go to different stations to get candy or other "healthier" options. They also have crafts and dancing too.
3. What are the must see's at DCA and DL?
DCA: Soarin' Over California, California Screamin', TSMM, Mulholland Madness, and the Play Parade. I think WDW's ToT is much better and Grizzly River Run is basically like Kali if you've been on those. You might also want to check out the Blue Sky Cellar to see what new things they'll be adding to the park.
DL: Indy, Space & BTM (don't remember how WDW's compares), POTC, IASW, Matterhorn, and Billy Hill and the Hillbillies.
4. Is two days at each park enough time to do everything?
I'd personally say that 2 days for both parks isn't enough to see every single thing, but if you only want to do certain things and not other, then you should do fine.
5. How is Universal studios and Knott's Berry farm and do they do anything special for halloween?
Universal has Halloween Horror Nights and Knott's has Halloween Haunt. From what I've heard, Knott's is scarier, depending if you like to get spooked or not. I'm not sure how Universal's is, but at Knott's they have different mazes that you can go into, some are 3D, where you can get scared, and some rides are also transformed where there'll be blood and have ppl pop out and scare you. HTH!