2) Get items like Burnout, Spark net, etc. Then, use the turbo controller to do a lot of damage. You can use them against Kongol at the end of disk one.
3) On the third disc have the talisman that prevents an instant death, equipped on Dart only. Do not put it on one of your other characters. This way you can use spirit potions on him to keep him in dragoon, and give him his magic back. Lloyd will attack only Dart but he won't die because of the talisman. Just keep using Final Burst, don't use Red-eye Dragon magic, it does the same amount of damage as Final Burst, it just eats your magic up. If he does attack another character than just have them heal themselves and the battle will be over a lot faster.
4) On the country that Disc 2 takes place in, go to the flower city that is plagued by the bandits. There is a bar in the town near the port. When you first go there, the man you need to talk to won't be there. At some point on Disc 2, though, I think it is after you beat the bandits, there will be a jester in there. Talk to him, and he will say that he saw stones just like yours in Lohan. Go there, talk to the merchant who sold you the water bottle, and he will sell you Kongol's Dragoon Spirit for 1000G.
5) When you fight Dart's father at the end of disc 4, you can defend against him and make the fight much easier if Dart has the red dragon armor, which nullifies fire attacks, and the red-eye stone, which cuts magic damage in half.