Funimation does have some manga available. However, it mainly focuses on anime content, so the manga collection is relatively limited and might not include the latest and most popular titles.
It's hard to say for sure. Funimation's content offerings change over time. You could search for it on the platform or look up the latest listings to find out if your love story is there.
Well, in these fanfictions, the immortal Naruto can be seen as a disruptor of the normal flow in the Negima world. His presence shakes up the power dynamics. Since he's immortal, he has a different perspective on life and death compared to the regular characters in Negima. This can lead to interesting interactions and storylines. For example, he could teach some of the Negima characters about his own experiences with loss and survival, even though he can't truly die. He might also introduce new combat techniques or ways of thinking that are foreign to the Negima universe.