Here you can calculate the IVs https://pokeassistant.com/main/ivcalculator
About your questions:
1. I'm not 100% sure, but some people reported it's possible to get half levels
2. There is no difference, given the two Dragonite have the same IVs
3. No, except that usually from eggs you get Pokémon at a level similar to your trainer level (up to a max of level 20), if you catch it in the wild, there is far more variability. The only thing that changes is the number of time you have to level it up