duel system is terrible, and high valyrian is overpower

High Valyrian taming power is culturally appropriate. But like onderion suggests, you should set the rule to hard before you start the game. I remember having problems with dragons when I started playing and saw someone suggest this and I haven't since. I mean, I haven't had a problem until the other week when my North born Stark-Targ line died out trying to hatch them. That was a low point. But other than that, it's great. 

The other option if you are playing a HV family like the Targs, or you are playing a family that just happens to have dragons, don't give out the eggs. Keep eggs for when your dragon dies or if someone else tames your dragon before your heir does. Otherwise there's the chance your family members won't tame them when you hand them out and then you run the risk of others trying to tame your dragons. Better to control the hatching than have a horde of dragons flying about.

The duelling I can't help you with because it drives me nuts too. I just pray to the Old Gods and the New and hope for the best.