Help

The answer to your 2nd qustion is change kluke's formation that that way she is out of the reach of his attack then weaken him and use shue's wind sword repeat this process until you defeat him.

2.
The dino has a weak spot on his horn; aim for it. Also train Shu and Jiro before hand also in basic black magic. Have Kluke and Jiro in the back row of the formation. Make sure Jiro's priority is Shu because the dinosaur can only attack Shu if he's in the frount row. Keep Shu's Hp up with Jiro's white magic! :-)
Hope it helps.
(I dunno how to get the force feilds off the treasure chests either)

For question #1 later in the game you get colored devices: blue, red, green, white and black. Getting the devices often invole a boss monster
You wont get your first device until you reach a point on disc two. To remove the barriers once you have the said device of said color simply press the A button twice on it and the barrier is no more.

#2 To defeat him I suggest getting your levels and skill ranks up first make sure you find the spell flare too the dino is weak against it.

For Question #1:
In the second disk you will get the devices that can unlock them. Try to remember their locations so you can get the items later.

For Question #2:
Let shu attack him on his horn then, go at your hardest to kill him.
P.s. I suggest you should put jiro and kluke in the back(formation when you press Y)