Highest score I've ever reached. Is it enough?

I generally go with 1000 spots a day so you prob have just about enough.

is that the team u use for arena? How many merges does ur cecilia have?

It's usually better to run infantary or anything but horses for arena to make a better score

Could be close but you should get in to Tier 20 but thats not the hard part staying in Tier 20 is the hard part and you should run infrantry units over horse units horse units have a lower BST than most infrantry units and you should always run the character you support on your offense team it also helps your BST and run maxed out skills