1. Necalli is very strong and plays a pretty straight forward game. He relies on good buttons in neutral and high damage mixups to make his opponents afraid to press buttons and challenge him. If you're capable of using his tools well and have an understanding of fundamental concepts like footsies, shimmies, and throw/meaty mixups you can beat any character using him.
2. It's difficult if it's your first fighting game, but if you've already got decent execution and knowledge of fighting game concepts it's very accessible. If you can play games like guilty gear, marvel, or KoF it's a walk in the park. Slow paced strategy where you live and die on a few individual decisions every round.
3. If you enjoy fighting games online/multiplayer then you'll like it. The gameplay is awesome, and the balance is good. If you prefer a single player experience I'd avoid it since there's almost no content.