As far as I know there are currently no living person on this planet claiming to be an Arhant.
Why is that?
1. Religion/dogma advises not to talk about attainments.
2. Person still feels like things are unfolding and evolving so doesn't feel 'done' enough to be Arhant.
3. Person doesn't want the attention for various reason.
4.
The 11th Army of Mara5. To become an Arhant is impossible.
6. Something else.
Regarding your other questions: Many have asked similar questions in the past, if you try and search the forum you might find some answers, but it's not easy to search and I don't have any links saved. Highly attained people will shy away from such questions as they tend to be more motivated answering questions directly related to practice. That being said you should check out the
happinessbeyondthought blog. The author answers many questions similar to yours asked by his readers.