Is this a good arena team?

Not if they are at 5 stars.

Since you don't have an all lvl 40 team, I assume you are fairly new to arena. A team of Celica, Azura and Fae + Bonus Hero will definately get you very far. Also you should train up you units to 40. It shouldn't take you very long. They seem good enough for stage 10 in the training tower. :)

At level 36 you may be able to tell the IVs. Keep in mind no stat can grow by any more than 4 and most will probably grow from 1-3. Depending on their general spread and how they've randomly leveled up, sometimes you can tell for certain and other times you can make an educated guess.

With that said, you really should get them to level 40 regardless.