1. Your entire team can be made up of Level 50 Pokémon, so the total level maximum would be 300.
2. Yes, but you would have to evolve your Combusken (You did spell it right!!) into Blaziken before it would be able to learn Blaze Kick from the Move Tutor.
3. Feebas is incredibly hard to find. In all that water on Route 119, there are only six "squares" that Feebas will appear on. The location of these squares is randomly set when you start a new game or when you change your "trendy phrase" at Dewford Town. So, once you find them on the Route 119 river, make sure you catch as many as you want, or just remember the location for future reference. You should be able to tell if a square that you are fishing at is a Feebas square within 3-4 tries. If you fish on a Feebas square, there is a 50% chance that the Pokémon that appears will be a Feebas. It doesn't matter which Rod you use.