Thank you for the art compliment! I'll relay it to my artist.
For range, it's tactics RPG range. It's the first one of your example, every point lets you move one point further in any orthogonal direction. Same with movement. If you charted it out, it's a big square with points jutting from the middle, like in Fire Emblem.
For Reimu, every time she moves, she also moves the ball into a space within 4 squares of her. From where the ball was at, it flies in a straight line to its new location.
Blast/Burst is an issue on my end, one of those word goofups you get in a thing like this. If it says either, it's an expanding cross shape.
Correct on Sanae. It's why her Perfect Spell card has her using every aspect of a selected spell card.
A Severe Wound would immediately injure a character, yes.
Scaling is the added "difficulty" for the amount of players.