EDIT: Reading up on Ahri, I wonder how Shirou will deal with her life-sucking tendency? Yes she is attempting to find ways to not harm people, but she does need the energy, and Shirou isn't the type to allow harm to come to innocents.
she can do it to non-lethal limits, also if we consider the Fate VN and the fact that sperm are technically "alive".. well.. you see where I'm going with this.
Looking at this picture again, those tails look fluffy. You think about it, but here Shirou is the luckiest Master for getting such an attractive Servant.
She'd be a Caster-class, right, or would there be other classes she could be summoned as?
No. Definitely Caster-class. Of course, one can be creative and add some details not shown in canon that would allow her to be almost any of the classes. Though it would be pushing it a bit considering everything about her just shouts out Caster-class.
This would be a nice comical doujin series. Indeed.
